refactor(slackify-changelog): Replace slackifyChangelog with slackifyText for improved handling and add truncation helper.

[M0nkeySan]

What

When a release has a changelog too big or a note is too big, homer can fail to send the message to slack due to the character limitation.

The current slackifyChangelog method is duplicated and can fail.
I created a new one slackifyText to remove the duplication, allow to specify the truncatedMessage and customize the maximum character allowed.

Also, I didn't change ReleaseOptions to avoid breaking change.

[codecov]

Codecov Report

❌ Patch coverage is 90.47619% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.94%. Comparing base (5af23ae) to head (5709b37).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/changelog/buildChangelogModalView.ts	50.00%	1 Missing ⚠️
...release/commands/create/utils/slackifyChangelog.ts	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #91      +/-   ##
==========================================
+ Coverage   78.63%   78.94%   +0.30%     
==========================================
  Files          95       95              
  Lines        1947     1947              
  Branches      343      348       +5     
==========================================
+ Hits         1531     1537       +6     
+ Misses        407      383      -24     
- Partials        9       27      +18     

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[cicoub13]

Good for me