fix: make indent commands return proper command result

[sehyod]

Problem
indent and unindent commands were returning true to block default behavior of Tab and Shift-Tab shortcuts. However this made the Backspace command believe that the content could be unindented, blocking the fallback behavior of the shortcut, which is merging the line with the previous one.

Solution
This changes the return result of indent and unindent commands back to the proper boolean indicating whether the command can run.
Tab and Shift-Tab shortcuts are now the one responsible for returning true to block the default behavior of these shortcuts.

Fixes #342

[codecov]

Codecov Report

Merging #343 (708f6b1) into main (af4e0b3) will decrease coverage by 0.07%.
The diff coverage is 18.18%.

@@            Coverage Diff             @@
##             main     #343      +/-   ##
==========================================
- Coverage   86.35%   86.28%   -0.07%     
==========================================
  Files         150      150              
  Lines        8491     8497       +6     
  Branches      957      957              
==========================================
  Hits         7332     7332              
- Misses       1148     1154       +6     
  Partials       11       11              

Files Changed	Coverage Δ
...ponents/tipTapNodes/notionBlock/commands/indent.ts	23.80% <0.00%> (ø)
...nents/tipTapNodes/notionBlock/commands/unindent.ts	27.02% <0.00%> (ø)
...ponents/tipTapNodes/notionBlock/NotionBlockNode.ts	74.17% <25.00%> (-1.37%)	⬇️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more