Fix set_state dropping False, 0, and None values

[Ten0]

Fixes #2531
Fixes #2464
Fixes #2492

Two bugs caused set_state (and other POST calls) to lose attribute values:

1. remove_literals used equality (==) to filter values, so 0 and 0.0 were removed alongside False (because 0 == False in Python). Fixed by switching to identity comparison (is).

2. clean_http_kwargs was applied globally to all HTTP methods, stripping False, None, and converting True to "true" even in POST JSON bodies where these are valid values. Replaced with a new self-contained clean_http_params_for_urlencode applied only to GET/DELETE query parameters; POST bodies are now passed transparently through the session's convert_json serializer. Removed the now-unused clean_kwargs function.

Also:

• Removed redundant clean_kwargs + remove_literals from websocket path; convert_json handles datetime serialization.
• Performance tracking now computes actual payload size per HTTP method.

I have tested this on my own HomeAssistant instance, and this does indeed solve the issue and it seems my home finally works properly without triggering exceptions on 4.5 with that change, so I might finally update from 4.4 once this is released. 🎉