refactor(yaml): cleanup `stringifyNode()`

[timreichen]

Changes This PR removes else block due to early return. It simplifies isObject(object) and Array.isArray(object) nesting. It moves duplicate logic up to avoid early compact check. ~It moves level inside the options object.~

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 94.11765% with 2 lines in your changes missing coverage. Please review.

Project coverage is 96.22%. Comparing base (b91817f) to head (07ebb0d). Report is 2 commits behind head on main.

Files	Patch %	Lines
yaml/_dumper_state.ts	94.11%	1 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5739      +/-   ##
==========================================
- Coverage   96.23%   96.22%   -0.02%     
==========================================
  Files         479      479              
  Lines       38719    38708      -11     
  Branches     5614     5614              
==========================================
- Hits        37262    37245      -17     
- Misses       1416     1421       +5     
- Partials       41       42       +1     

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