proposal for overriding values inside structured data files

[sophiefeifeifeiya]

What type of PR is this?

/kind design /kind documentation

What this PR does / why we need it: Overriding values in structured data files (e.g., JSON, YAML) to simplify modifications.

Which issue(s) this PR fixes: Fixes #5330

Special notes for your reviewer: Related PR: #5329

Does this PR introduce a user-facing change?:

Introduced `PlaintextObjectOverrider`  for overriding values in YAML or JSON plaintext objects.