feat: add Block::title_top and Block::title_top_bottom

[joshka]

This adds the ability to add titles to the top and bottom of a block
without having to use the Title struct (which will be removed in a
future release - likely v0.28.0).

Fixes a subtle bug if the title was created from a right aligned Line
and was also right aligned. The title would be rendered one cell too far
to the right.

Block::bordered()
    .title_top(Line::raw("A").left_aligned())
    .title_top(Line::raw("B").centered())
    .title_top(Line::raw("C").right_aligned())
    .title_bottom(Line::raw("D").left_aligned())
    .title_bottom(Line::raw("E").centered())
    .title_bottom(Line::raw("F").right_aligned())
    .render(buffer.area, &mut buffer);
// renders
"┌A─────B─────C┐",
"│             │",
"└D─────E─────F┘",

Addresses part of #738

[codecov]

Codecov Report

Attention: 14 lines in your changes are missing coverage. Please review.

Comparison is base (91040c0) 92.0% compared to head (a0bd2b2) 91.9%.

Files	Patch %	Lines
src/widgets/block.rs	73.5%	14 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #940     +/-   ##
=======================================
- Coverage   92.0%   91.9%   -0.1%     
=======================================
  Files         61      61             
  Lines      15636   15703     +67     
=======================================
+ Hits       14390   14436     +46     
- Misses      1246    1267     +21     

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[kdheepak]

When should we mark block::Title as deprecated?

[joshka]

It's a bit complicated. We would have to make everything that calls it work right, but probably before the next major release.

[Valentin271]

"┌A─────B──────C",
"│             │",
"└D─────E──────F",

Isn't it weird that C and F and all the way to the right (over the corners) but A and D keeps the corners? I naturally would expect this code to render all four corners the same way.

[joshka]

Isn't it weird that C and F and all the way to the right (over the corners) but A and D keeps the corners? I naturally would expect this code to render all four corners the same way.

This was a bug and I forgot to update the commit message

fixed