fix(core): Address UTF-8 character boundary issues in LineBreaker

[iamchanii]

Summary:
This PR integrates the unicode-segmentation crate to address issues related to UTF-8 character boundaries in the LineBreaker struct. The changes ensure that string documentation is formatted safely without encountering byte index errors. The code now correctly iterates over grapheme clusters, thus maintaining valid character boundaries during string manipulation.

Before the change, the added test case causes a panic.

Issue Reference(s):
N/A

Build & Testing:

• I ran cargo test successfully.
• I have run ./lint.sh --mode=fix to fix all linting issues raised by ./lint.sh --mode=check.

Checklist:

• I have added relevant unit & integration tests.
• I have updated the documentation accordingly.
• I have performed a self-review of my code.
• PR follows the naming convention of <type>(<optional scope>): <title>

[tusharmath]

Thanks @iamchanii 🙌

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.32%. Comparing base (4cf48a1) to head (cc76682).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3228      +/-   ##
==========================================
+ Coverage   86.30%   86.32%   +0.01%     
==========================================
  Files         282      282              
  Lines       28761    28798      +37     
==========================================
+ Hits        24823    24860      +37     
  Misses       3938     3938              

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