Enhance Notification Broadcasts Admin Panel

[davelopez]

Fixes #17010

• Includes some explanation texts for notification management.
• Allows to filter broadcast notifications by status
• Clarifies/simplifies the language around dates and times
• Refactors some components and includes some tests

How to test the changes?

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.