feat: Add an extensible API for stream schema sources

[edgarrmondragon]

Feature scope

Taps (catalog, state, tests, etc.)

Description

With #2743 and eventual removal of support for schema file paths in constructors, we'll be on the path to support a better public API for arbitrary schema sources that prevents users from reinventing the wheel.

An example of how this might look:

openapi_schema = OpenAPISchema("https://.../openapi.json")  # might also accept a 'Traversable' importlib.resources object

class ProjectsStream(RESTStream):
    name = "projects"
    path = "/projects"
    schema_source = openapi_schema("ProjectListItem")  # a JSON Schema ref

Related:

• Leverage schema and other API details from OpenAPI spec file #308
• Improved support for OpenAPI sources #2190
• Alternative implementation for OpenAPI: https://github.com/edgarrmondragon/tap-neon/blob/60c58b4961d4cac67f1fb8e615ec37b8340a9c15/tap_neon/streams.py#L23-L31