[JENKINS-67456] add check that pattern is valid

[mawinter69]

performs a check of the pattern when the field looses focus
Additionally check when pressing the add button if the pattern is valid to avoid that an invalid pattern can be added at all.
see JENKINS-67456

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[kuoruan]

The escape function is deprecated https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/escape
Can we use encodeURIComponent instead?

[NotMyFault]

The escape function is deprecated https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/escape Can we use encodeURIComponent instead?

Interesting, feel free to submit a new PR addressing the deprecation. I'm not a maintainer of this plugin.