✨ add support for custom httpx client for V1 and V2

[sebastianMindee]

Description

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Requires a change to the official Guide documentation.

[ianardee]

OK for a single call, but what happens when multiple calls are made?

Also:

• what happens to the client, does it close by itself, does the user need to close it?
• does threading still work now that the client is a class variable?

More explicit testing of failure points need to be added.

[sebastianMindee]

what happens to the client, does it close by itself, does the user need to close it?

Good point, I had forgotten to add the garbage collection. Also, if they aren't using a context manager they have to manage it themselves, but not much we can do.

does threading still work now that the client is a class variable?

Yes: encode/httpx#1633

More explicit testing of failure points need to be added.

Did so, tell me if you think more are warranted