[build] Cleanup to cmakelists and includes

[CastagnaIT]

Description

The main goal is to remove the long list of sources declared to the main CMakeLists.txt file that are starting to get very long, and then add a CMakeLists file to each subfolder

since it is strictly related i taken the opportunity to improve also the includes

The XML_STATIC define has been removed from the main CMakeLists because was needed only for the old expat library that now dont exists anymore

Motivation and context

Now that the decrypter refactor has been done i try to do some more deep cleanup

How has this been tested?

played wv drm stream on windows and android

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• I have read the Contributing document
• My code follows the Code Guidelines of this project
• My change requires a change to the Wiki documentation
• I have updated the documentation accordingly

[glennguy]

great!