fix(type-safe-api): fix syntax error for python runtime request parameters with descriptions

[cogwirrel]

Descriptions in Python request parameters would previously render invalid python syntax as quotes were escaped as ". Use triple curly braces ({{{vendorExtensions.x-py-typing}}}) to ensure these are rendered correctly.

Additionally, field references can only be used once per field in a pydantic model, and since fields with descriptions include the field in the type annotation these would fail at runtime when another field is used in the assignment, ie:

foo: Annotated[StrictStr, Field(..., description="...")] = Field(alias='foo')

The above causes a runtime error (ValueError: `Field` default cannot be set in `Annotated` for ... - pydantic/pydantic#3991 )

We therefore remove the assignment of a Field value, which is ok since the alias is not required as the handler wrapper already constructs a dict with the paramNames as keys rather than the baseNames which are in the raw request. ie we already do:

"{{paramName}}": coerce_parameter("{{baseName}}", ...)

Which means we even load renamed parameters (like a header x-foo-bar from a dictionary which names it as x_foo_bar).

Fixes #609