Convert sentry_sdk type annotations into the modern format

[zsol]

Description

This PR converts all Python 2-style type annotations (in comments) into Python 3-style annotations (after : tokens, and inside the AST).

There's a large amount of changes in here, apologies for that. I generated these changes using:

1. A LibCST codemod to do the bulk of the work: uv run --with libcst python -m libcst.tool codemod convert_type_comments.ConvertTypeComments --no-format -j1 sentry_sdk
2. Some manual fixups here and there (see below)
3. Run com2ann to fix the rest: uvx com2ann sentry_sdk
4. Reformat: uvx ruff format sentry_sdk

Manual changes

• The LibCST command made a bunch of silly mistakes like turning foo = None # type: Foo # noqa into foo: "Foo # noqa" = None, which were trivial to fix
• When turning foo = None # type: Foo into foo: Foo = None, mypy starts raising an error on the second form - I suppressed these using type: ignore[assignment]

Test plan

mypy should continue being green, as evidenced by running uvx tox -e linters