Configuration to display an application banner

[josegar74]

In certain cases can be relevant to display a banner in the application to inform users, for example of a maintenance task.

This change request adds a new setting to enable an application banner and configure the text to display.

The banner is displayed in the public pages.

Checklist

• [X] I have read the contribution guidelines
• [X] Pull request provided for main branch, backports managed with label
• [ ] Good housekeeping of code, cleaning up comments, tests, and documentation
• [X] Clean commit history broken into understandable chucks, avoiding big commits with hundreds of files, cautious of reformatting and whitespace changes
• [X] Clean commit messages, longer verbose messages are encouraged
• [ ] API Changes are identified in commit messages
• [ ] Testing provided for features or enhancements using automatic tests
• [ ] User documentation provided for new features or enhancements in manual
• [ ] Build documentation provided for development instructions in README.md files
• [ ] Library management using pom.xml dependency management. Update build documentation with intended library use and library tutorials or documentation