feat(yaml): pass depth to sortKeys callback in stringify

[tomas-zijdemans]

Resolves: #6898

I'm not sure if this is a fix or a feat 🤷

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.39%. Comparing base (432d3f3) to head (14a667a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7001   +/-   ##
=======================================
  Coverage   94.39%   94.39%           
=======================================
  Files         629      629           
  Lines       50262    50263    +1     
  Branches     8870     8870           
=======================================
+ Hits        47443    47445    +2     
  Misses       2251     2251           
+ Partials      568      567    -1     

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[bartlomieju]

Clean, minimal change. Two notes:

1. This is additive functionality (new parameter), not a bug fix — should be feat(yaml) rather than fix(yaml), since it's a semver-minor change for a stable package.
2. The type signature change from (a: string, b: string) => number to (a: string, b: string, depth: number) => number is backwards-compatible at runtime (extra args are ignored), but TypeScript users with explicitly typed callbacks may notice the signature difference. Minor concern.

Implementation and test look good.

[tomas-zijdemans]

Title updated as requested