Add input validation for params dictionary

[ompat5]

Changes Made

• Added a new helper function validate_html_dictionary() to recursively validate HTML content within dictionaries.
• Added validate_html_list() to handle lists that may contain other nested lists or dictionaries.
• Created a PROPERTIES_EXEMPT set to exclude certain properties from validation where HTML is expected or unnecessary to sanitize.
• Wrapped validation logic under an environment variable (ADR_VALIDATION_BETAFLAG_ANSYS) to allow toggling validation on/off for easier testing and to avoid affecting users.

User Story: https://tfs.ansys.com:8443/tfs/ANSYS_Development/Portfolio/_workitems/edit/1249514

[codecov-commenter]

Codecov Report

❌ Patch coverage is 83.78378% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.58%. Comparing base (5ecad29) to head (9a0ed7d).

Files with missing lines	Patch %	Lines
src/ansys/dynamicreporting/core/common_utils.py	93.10%	1 Missing and 1 partial ⚠️
...ansys/dynamicreporting/core/serverless/template.py	33.33%	1 Missing and 1 partial ⚠️
...nsys/dynamicreporting/core/utils/report_objects.py	60.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #431      +/-   ##
==========================================
+ Coverage   81.57%   81.58%   +0.01%     
==========================================
  Files          28       28              
  Lines        7990     8027      +37     
  Branches     1477     1492      +15     
==========================================
+ Hits         6518     6549      +31     
- Misses       1002     1005       +3     
- Partials      470      473       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[margalva]

@ompat5 can you please add tests for this? Thanks.