feat: make context have generic client types

[AstreaTSS]

Pull Request Type

• Feature addition
• Bugfix
• Documentation update
• Code refactor
• Tests improvement
• CI/CD pipeline enhancement
• Other: [Replace with a description]

Description

This PR makes the contexts a generic type holding ClientT, a TypeVar that represents clients and subclasses. Taking advantage of PEP 696, this PR ensures a grand total of 0 typings are broken by using default (thanks to typing_extensions).

This allows for people to type out their command functions in a pretty clean way if they make a subclass of Client - previously, you would have to make your own Context class that replaced the Client references with your own, but now it's as easy as the test scenario.

This doesn't cover every possible thing that could use ClientT, and especially not everything that could use TypeVar(default=X), but it's a start

Changes

• Introduce ClientT in const. To get around circular imports, during runtime, all ClientT is is ClientT = TypeVar("ClientT"), but when type checking, it's far more accurate.
• Use ClientT in the Contexts as a generic.
• Adjust Client's custom contexts to use the new generic property.

Related Issues

Test Scenarios

import interactions as ipy

class MyBotClient(ipy.Client):
    def say_hi(self) -> None:
        print("Hello!")

@ipy.slash_command()
async def test(ctx: ipy.SlashContext[MyBotClient]):
    ctx.bot.say_hi()  # typehints perfectly, instead of being unknown

Python Compatibility

• I've ensured my code works on Python 3.10.x
• I've ensured my code works on Python 3.11.x

Checklist

• I've run the pre-commit code linter over all edited files
• I've tested my changes on supported Python versions
• I've added tests for my code, if applicable
• I've updated / added documentation, where applicable