feat(widgets): Rename StatefulWidget::render to render_stateful

[joshka]

This change renames the StatefulWidget::render method to
render_stateful to avoid conflicts with the Widget::render method.

Often both the Widget and StatefulWidget traits are in scope, and
when calling the render method on a StatefulWidget the compiler
cannot determine which trait to use. This change resolves that issue by
renaming the StatefulWidget::render method to render_stateful.

The StatefulWidget::render method is still available, but it is
deprecated. A default implementation of render_stateful is provided
that calls the deprecated render method.

Callers should update their code to use render_stateful instead of
render.
implementors of the StatefulWidget trait should update their
implementations to implement render_stateful instead of render, and
provide an implementation of render that calls render_stateful.

This change is non-breaking. The deprecated render method will be
removed in a future release of Ratatui (likely 0.29.0).

Addresses part of a problem raised in
#996

[codecov]

Codecov Report

Attention: Patch coverage is 78.94737% with 8 lines in your changes missing coverage. Please review.

Project coverage is 94.2%. Comparing base (4bfdc15) to head (5c66a94).
Report is 7 commits behind head on main.

Files	Patch %	Lines
src/widgets/list.rs	71.4%	4 Missing ⚠️
src/widgets/table/table.rs	75.0%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1183     +/-   ##
=======================================
- Coverage   94.3%   94.2%   -0.1%     
=======================================
  Files         60      60             
  Lines      14679   14710     +31     
=======================================
+ Hits       13843   13862     +19     
- Misses       836     848     +12     

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[kdheepak]

Similar to the other PR, I think we could do render_with_state() instead, but I'm fine with render_stateful(). Again, worth checking in with other maintainers for a second opinion.

[joshka]

Similar to the other PR, I think we could do render_with_state() instead, but I'm fine with render_stateful(). Again, worth checking in with other maintainers for a second opinion.

likewise - I'm 55/45 on stateful vs with_state here too.

[joshka]

Holding for resolution of discussion at https://forum.ratatui.rs/t/naming-render-traits-methods/68