Storage: Add extend_json Tag for Enhanced JSON Field Handling in bulk_update Operations

[rabbull]

In #6587, it was determined that when performing bulk_update operations on JSON fields like extra, the existing JSON should be extended rather than overwritten. To address this, this PR introduces a new tag, extend_json, that controls how bulk_update handles JSON fields. By default, extend_json is set to False, ensuring backward compatibility. When explicitly enabled, bulk_update merges the provided JSON with the existing JSON field, following to the RFC 7386 - JSON Merge Patch standard. This feature supports both SQLite and PostgreSQL backend.

Note:

1. This implementation currently assumes that only attributes and extra are JSON fields of interest, and few additional JSON fields will be introduced. As a result, automatic detection of JSON fields is not implemented.
2. The bulk_update logic for the SQLite DOS backend currently resides in PsqlDosBackend. A dirty workaround has to be added in PsqlDosBackend to address the differences between SQLite and PostgreSQL. This is also stated in a comment block in the code.

[unkcpz]

If some test hang up, it might benefit from #6674.

[codecov]

Codecov Report

Attention: Patch coverage is 90.16393% with 6 lines in your changes missing coverage. Please review.

Project coverage is 76.60%. Comparing base (7387056) to head (2db8385).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aiida/storage/psql_dos/utils.py	42.86%	4 Missing ⚠️
src/aiida/storage/psql_dos/backend.py	96.78%	1 Missing ⚠️
src/aiida/storage/sqlite_temp/backend.py	95.24%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6659      +/-   ##
==========================================
- Coverage   78.00%   76.60%   -1.39%     
==========================================
  Files         563      563              
  Lines       41766    41812      +46     
==========================================
- Hits        32574    32025     -549     
- Misses       9192     9787     +595     

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