Round 2: Add doc_blocks to manifest for nodes and columns

[aranke]

Problem

#11224 (Add doc_blocks to manifest for nodes and columns) would have failed in a scenario where the user had already specified doc_blocks at the node or column level as outlined in #11282 (quick functional test on doc_blocks issue).

Solution

• Set doc_blocks=[] during serialization if either:
  • doc_blocks is not a list
  • not every element in doc_blocks is a str
• Add tests for the scenarios above, which should satisfy the Mashumaro type of list[str]

Checklist

• I have read the contributing guide and understand what's expected of me.
• I have run this code in development, and it appears to resolve the stated issue.
• This PR includes tests, or tests are not required or relevant for this PR.
• This PR has no interface changes (e.g., macros, CLI, logs, JSON artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX.
• This PR includes type annotations for new and modified functions.

[codecov]

Codecov Report

Attention: Patch coverage is 93.18182% with 3 lines in your changes missing coverage. Please review.

Project coverage is 88.89%. Comparing base (7f32e42) to head (7451ca9).
Report is 1 commits behind head on main.

❌ Your patch status has failed because the patch coverage (31.81%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11294      +/-   ##
==========================================
- Coverage   88.95%   88.89%   -0.06%     
==========================================
  Files         189      189              
  Lines       24139    24171      +32     
==========================================
+ Hits        21473    21487      +14     
- Misses       2666     2684      +18     

Flag	Coverage Δ
integration	86.15% <93.18%> (-0.14%)	⬇️
unit	62.53% <31.81%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
Unit Tests	62.53% <31.81%> (-0.03%)	⬇️
Integration Tests	86.15% <93.18%> (-0.14%)	⬇️

[emmyoop]

Looks good - let just add a bit more context as to why we're updating to an empty list in some cases so future us has a better idea of what's happening.