refactor: simplify json_like trait

[meskill]

Summary:
Simplify JsonLike associated type constraints according to TODO in the code. This is doable after serde_json_borrow update PSeitz/serde_json_borrow#19

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>

[codecov]

Codecov Report

Attention: Patch coverage is 57.89474% with 8 lines in your changes missing coverage. Please review.

Project coverage is 87.13%. Comparing base (d473af2) to head (80b9490).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/core/json/serde.rs	0.00%	5 Missing ⚠️
src/core/json/borrow.rs	60.00%	2 Missing ⚠️
src/core/json/graphql.rs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2780   +/-   ##
=======================================
  Coverage   87.13%   87.13%           
=======================================
  Files         254      254           
  Lines       25144    25144           
=======================================
  Hits        21909    21909           
  Misses       3235     3235           

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