[BugFix] Add json_schema_extra With Choices To Provider 'period' Field

[deeleeramone]

1. Why?:

   • Parameters defined as a Literal do not have a list of choices for the schema.

2. What?:

   • Defines the Literal choices in json_schema_extra for each provider's period field in balance/cash/income endpoints.
   • Cleans up the "growth" models that are only used by FMP to be more like the balance/cash/income models.
   • Adds json_schema_extra={"x-unit_measurement"} wherever was missing.

3. Impact:

   • Does not change any params.
   • Pro does not use the growth endpoints, the cleanup here will not impact existing widgets.
   • Improved schema definitions that will help anyone relying on openapi.json or reference.json
   • Rename a couple of Polygon fields to align with others.

4. Testing Done:

   • Integration and unit tests.
   • 'regular' usage.

[hjoaquim]

A lot of changes. Please merge only after release 4.2.1

[hjoaquim]

For future reference:
For the CLI to leverage custom choices, one only need to populate the json_schema_extra with them if it's not possible to use such options inside the Literal - cases where we want to leverage comma separated lists and as such the type need to be str instead of Literal.
Here, we're just duplicating the same info.

[deeleeramone]

From what I've experienced, the act of defining almost any Literal is an exercise in duplication, and this appears to be a limitation of Python 3.9, because you cannot dynamically define a Literal.