Add individual rotation time for each page

[KristjanESPERANTO]

The aim of this PR is to introduce an option to set an individual rotation time for each page.

Here is an example to give you an idea - it sets an individual time for page 2:

    {
      module: 'MMM-pages',
      config: {
        timings: {
          default: 5000,
          2: 20000
        },
        modules: [
          ['page0'],    // ---> 5 sec
          ['page1'],    // ---> 5 sec
          ['page2'],    // ---> 20 sec
          ['page3'],    // ---> 5 sec
        ]
      }
    },

I tested it with Module name based configuration and Class based configuration.

Note 2025-03-23: Updated to follow requests from #46.

[edward-shen]

See my comment for my thoughts on the PR