Deprecate instantiation of subclass specs in Any and missing --print_%s deprecation warning

[mauvilsa]

What does this PR do?

Two deprecations for v5.0.0:

Instantiation of subclass specs in Any

When a value for a type that accepts anything (Any or Unvalidated<...>) is a valid
subclass spec, instantiate_classes currently builds the class. This is deprecated: from
v5.0.0 the subclass spec will be kept as is, leaving it to the code that receives it to
decide whether to instantiate. Instantiating is a security risk, since it means a config
can instantiate any class.

A new instantiate_subclass_spec_in_any setting in set_parsing_settings allows opting
into the future behavior now (False, silencing the warning) or keeping the current one
(True, discouraged). The setting defaults to None, which behaves as True and emits
the deprecation warning; in v5.0.0 the default becomes False and the deprecated path is
removed.

--print_config to --print_%s

The name change announced in v4.35.0 never emitted a warning. One is now raised (under
JSONARGPARSE_DEPRECATION_WARNINGS=all) when the config argument is not named config,
so the print config argument name will change in v5.0.0.

Before submitting

• Did you read the contributing guideline?
• If you used a coding agent, did you fully understand and validate all generated code and ensure it follows the contributing guidelines?
• Did you update the documentation? (readme and public docstrings)
• Did you write unit tests such that there is 100% coverage on related code? (required for bug fixes and new features)
• Did you verify that new and existing tests pass locally?
• [n/a] If this is a bug fix, did you verify that the tests fail without the code fix?
• Did you make sure that all changes preserve backward compatibility?
• Did you update the CHANGELOG including a pull request link? (not for typos, docs, test updates, or minor internal changes/refactors)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (553c8b0) to head (0b68236).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #955   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           27        27           
  Lines         8444      8464   +20     
=========================================
+ Hits          8444      8464   +20     

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud