fix(block)!: remove title

[TadoTheMiner]

This PR is a draft. Firstly, it's a breaking change, secondly, a test fails, because for some reason instead of None the line has Some(Reset) in block_title_style. I couldn't find out what causes that, but I will try to address that issue.

BREAKING_CHANGE: use line instead

[TadoTheMiner]

This PR fixes #738

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.4%. Comparing base (b7778e5) to head (c62d4ec).

Additional details and impacted files

@@          Coverage Diff           @@
##            main   #1012    +/-   ##
======================================
  Coverage   89.4%   89.4%            
======================================
  Files         61      60     -1     
  Lines      15430   15319   -111     
======================================
- Hits       13799   13703    -96     
+ Misses      1631    1616    -15     

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[joshka]

Before going further on this, I want to call your attention to the checklist in the attached issue.
It's a good idea to split this up into a few PRs:

• add the top_ and bottom_ fields and setters, update the rendering to use these instead of the current titles field (non breaking change)
• Implement From<Title> for Line
• Mark all deprecations and write up a transition guide for the change in BREAKING changes
• Remove existing deprecated setter
• Change Block::title to accept Into instead of Into<Title>
  in a later release remove the deprecated stuff.

The plan might not be 100% accurate, but the rationale for doing things this way is that we want to provide a way to notify users of the library that things will change in the future. For this we use deprecation attributes that will make warnings on builds. This means that it's important to take a step back and do this step by step and not as one big change.

The generalized breaking change process is:

• Make some change that will be the future state that doesn't break
• Mark the existing code as deprecated with a note to use the new way
• Release a couple of major versions with that new code letting users update when they can (we often make this about 2 releases, which is 2-4 months warning)
• Finally remove the existing code (or make the breaking change)

The thing to remember is to be empathetic to the maintainers of applications and try to make their lives easy. If we break things, often we'll hear from app users instead of app maintainers (or just give a general bad impression that ratatui is buggy).

This PR as it stands is a problem as it changes things without notifying app devs. So, let's jump back to the linked issue and keep talking about the order of things instead of jumping to this implementation.

[TadoTheMiner]

Have you reviewed the transition guide?

[joshka]

Have you reviewed the transition guide?

This PR won't be merged as it's sort of the part 2 or 3 of a several part series and part 1 doesn't exist yet.

1. Make a release that adds the new methods that will replace the existing ones (e.g. 0.27.0 adds title_top() and title_bottom(). Mark the deprecation in that release. This is a non-breaking change.
2. Let that bake for a while and watch apps upgrade to the new methods when they see warnings about things breaking soon.
3. Make a later release (0.29.0) that removes / changes the old method and removes the Title struct (i.e. this PR)

[TadoTheMiner]

Have you reviewed the transition guide?

1. Make a release that adds the new methods that will replace the existing ones (e.g. 0.27.0 adds title_top() and title_bottom(). Mark the deprecation in that release. This is a non-breaking change.

Already did. So I should make a separate branch for them?

[joshka]

Have you reviewed the transition guide?

1. Make a release that adds the new methods that will replace the existing ones (e.g. 0.27.0 adds title_top() and title_bottom(). Mark the deprecation in that release. This is a non-breaking change.

Already did. So I should make a separate branch for them?

The first step needs to be in an entirely separate PR, merged into main, and then released into crates.io. We merge PRs as a single unit generally, not individual commits. It's possible that I've misunderstood what you've done. Can you write it out in a bit more detail about what you've done for step 1?

[TadoTheMiner]

Can you write it out in a bit more detail about what you've done for step 1?

Well I didn't deprecate the old functions I've just removed. Will submit a PR that just adds the functions and deprecates the old ones.