More proper deprecation warnings

[akx]

Description

This PR improves and deduplicates a whole bunch of deprecation warnings around Gradio, following up on #4203, by:

• adding some plumbing:
  • a new GradioDeprecationWarning warning class (since DeprecationWarnings aren't visible by default)
  • a find_user_stack_level helper inspired by Pandas' similar helper that allows an user of warnings.warn() to find the first user code stack level (so warnings point at user code, not at Gradio internals)
• refactoring:
  • adding and using a single warn_deprecation helper that uses the above utilities
  • using a single warn_style_method_deprecation for the repeated .style() warning message from Remove style parameter #4374
  • using a single warn_output_deprecation for the repeated output warning message from [BIG PR] Gradio blocks & redesigned components #880
  • using a single warn_input_deprecation for the repeated input warning message from [BIG PR] Gradio blocks & redesigned components #880

The end result is that the user gets pinpointed warnings, e.g.

modules/ui.py:1058: GradioDeprecationWarning: The `style` method is deprecated. Please set these arguments in the constructor instead.
  with gr.Row().style(equal_height=False):
modules/ui.py:1090: GradioDeprecationWarning: The `style` method is deprecated. Please set these arguments in the constructor instead.
  with gr.Row().style(equal_height=False):

instead of having to hunt around for these around their codebase since a single warning is only shown once by default.

Also, there's less code than before, in total.

🎯 PRs Should Target Issues

This PR does not target an issue, since this was yet another small annoyance I came across while attempting to upgrade Gradio in the stable-diffusion-webui project.

I can create an issue to say that "warnings aren't helpful", if that... helps.

[gradio-pr-bot]

All the demos for this PR have been deployed at https://huggingface.co/spaces/gradio-pr-deploys/pr-4694-all-demos

[abidlabs]

Thanks @akx! LGTM + appreciate the more helpful warnings