HBASE-29223 Migrate Master Status Jamon page back to JSP (#6875)

The JSP code is equivalent to the Jamon code, just changed the syntax back to JSP.
Request attributes are used to transfer data between JSP pages.
Tried to preserve the code as much as possible but did some changes:

Sub-templates were usually extracted to separate JSP file (and included with `<jsp:include`), in some case it was extracted as Java method.

Extracted some sections from master page to separate JSP pages:
- Software Attributes
- Warnings

Extracted the long JavaScript from the master page which executes on page load to separate JS file.

Extracted some frequently used static methods to a new util class: `MasterStatusUtil`. Also added unit tests for the static methods in `MasterStatusUtil`. 

Changed the Master Status page back to `/master.jsp` again. Now made sure that `/master-status` redirects to `/master.jsp`.

Signed-off-by: Istvan Toth <stoty@apache.org>

Author: PDavid