feat: add Bootstrap 5 theme support

[alex-tw-lam]

Description

This PR integrates Bootstrap version 5.3.3 into the JSON Editor Parameter plugin. The changes include:

• pom.xml:
  • Added a new dependency for Bootstrap.
  • Configured an artifact item to include the minified Bootstrap CSS (bootstrap.min.css), with file mappers to flatten and rename the file.
• index.jelly:
  • Updated to include the Bootstrap adjunct so that the minified CSS is loaded with the page.

These modifications ensure that the Bootstrap styles are available and correctly applied in the plugin’s UI.

Testing done

• Build Verification: Successfully built the project using Maven, confirming that the Bootstrap dependency and file mapping are correctly processed.
• Manual Testing: Deployed the plugin in a test Jenkins instance and verified that the bootstrap.min.css file is correctly included and applied. The UI rendered as expected with the new styling changes.
• Regression Check: Performed a basic regression test to ensure no other functionality was affected by these changes.

Submitter checklist

• Made sure to open from a topic/feature/bugfix branch.
• Ensured that the pull request title represents the desired changelog entry.
• Described the changes made and their purpose.
• Linked to relevant issues in GitHub or Jira (if applicable).
• Linked to any relevant pull requests, especially upstream and downstream changes.
• Confirmed that tests have been provided or manual testing was performed to demonstrate the feature works or the issue is fixed.

[alex-tw-lam]

Addresses #9