Implement default metadata for components and adapters

This implements default metadata as specified in landtrans/landtech/management#233

@muellese Should we somehow try to get the actual slot metadata (like units, grid, ...) into here too? Not sure how to represent grids, but it could IMO be useful.
Done.

TODO:

• Update docs
• Add book section
• Overwrite/implement for existing components and adapters
• Update CHANGELOG
• Merge !273 (merged)

Example

{'adapters': {'Scale@2391719058640': {'class': 'finam.adapters.base.Scale',
                                      'in_info': {'grid': 'NoGrid (0D)',
                                                  'units': ''},
                                      'name': 'Scale',
                                      'out_info': {'grid': 'NoGrid (0D)',
                                                   'units': ''}},
              'Scale@2391719059168': {'class': 'finam.adapters.base.Scale',
                                      'in_info': {'grid': 'NoGrid (0D)',
                                                  'units': ''},
                                      'name': 'Scale',
                                      'out_info': {'grid': 'NoGrid (0D)',
                                                   'units': ''}}},
 'components': {'MockupComponent@2391719110688': {'class': 'test_schedule.MockupComponent',
                                                  'inputs': {},
                                                  'name': 'MockupComponent',
                                                  'outputs': {'Output': {'class': 'finam.sdk.output.Output',
                                                                         'has_targets': True,
                                                                         'info': {'grid': 'NoGrid (0D)',
                                                                                  'units': ''},
                                                                         'is_static': False,
                                                                         'name': 'Output'}}},
                'MockupDependentComponent@2391719111408': {'class': 'test_schedule.MockupDependentComponent',
                                                           'inputs': {'Input': {'class': 'finam.sdk.input.Input',
                                                                                'info': {'grid': 'NoGrid (0D)',
                                                                                         'units': ''},
                                                                                'is_static': False,
                                                                                'name': 'Input'}},
                                                           'name': 'MockupDependentComponent',
                                                           'outputs': {}},
                'MockupDependentComponent@2391719111696': {'class': 'test_schedule.MockupDependentComponent',
                                                           'inputs': {'Input': {'class': 'finam.sdk.input.Input',
                                                                                'info': {'grid': 'NoGrid (0D)',
                                                                                         'units': ''},
                                                                                'is_static': False,
                                                                                'name': 'Input'}},
                                                           'name': 'MockupDependentComponent',
                                                           'outputs': {}}},
 'links': [{'from': {'component': 'MockupComponent@2391719110688',
                     'output': 'Output'},
            'to': {'adapter': 'Scale@2391719059168'}},
           {'from': {'component': 'MockupComponent@2391719110688',
                     'output': 'Output'},
            'to': {'component': 'MockupDependentComponent@2391719111696',
                   'input': 'Input'}},
           {'from': {'adapter': 'Scale@2391719058640'},
            'to': {'component': 'MockupDependentComponent@2391719111408',
                   'input': 'Input'}},
           {'from': {'adapter': 'Scale@2391719059168'},
            'to': {'adapter': 'Scale@2391719058640'}}],
 'time_frame': [datetime.datetime(2000, 1, 1, 0, 0), None]}

src/finam/sdk/adapter.py

@@ -70,10 +70,32 @@ class Adapter(IAdapter, Input, Output, ABC):
     @property
     def metadata(self):
         """
-        The adapter's meta data.
+        The adapter's metadata.
         Will only be called after the connect phase of the composition.
 
-        Returns an empty ``dict`` unless overwritten in adapter implementation.
+        Adapters can overwrite this property to add their own specific metadata:
+
+        .. code-block:: Python
+            class MyAdapter(Adapter):
+
+                @property
+                def metadata(self):
+                    // Get the default metadata
+                    md = super().metadata
+
+                    // Add your own metadata
+                    md["my_field"] = "some value"
+
+                    // Return the dictionary
+                    return md
+
+
+        Returns
+        -------
+        dict
+            A ``dict`` with the following default metadata:
+              - ``name`` - the component's name
+              - ``class`` - the component's class
         """
         meta = {
             "name": self.name,