feat(developer): kmc-convert: new conversion xkb->kmn 😎 - #15922

The next conversion (kmc-convert: xkb->kmn ):

This is to decice on a possibly new foder structure:

As a starting point we created an additional runable version of kmc-convert: keylayout ->kmn both being identical:

• a new XkbToKmnConverter has been added and used in Converter/ConverterClassFactory
• new src files have been created (which are exact copies from src files of the conversions keylayout ->kmn )
• new test src files have been created (which are exact copies from test src files of the conversions keylayout ->kmn )
• new test data files have been created (which are exact copies from test data files of the conversions keylayout ->kmn )

For kmc-convert there are 9 conversion modules but we may reuse some files:
there are:

• 6 for reading ( e.g. keylayout-file-reader.ts, xkb-file-reader.ts,...) ,
• 9 for converting (e.g. keylayout-to-kmn-converter.ts, xkb-to-kmn-converter.ts,...)
• 2 for writing . (kmn-file-writer.ts ,ldml-file-writer.ts)

To prevent duplicate files and to obtain a cleaner structure of src, test-src and test-data files we might create a new folder structure which would suit all present and future conversions well.

This PR proposes:

• creation of 3 src- subfolders read, convert and write to sort src according to function
• creation of 3 test-src subfolders read, convert and write to sort tests according to function
• creation of a test-data subfolder for each conversion

@keymanapp-test-bot skip