[MUSIC] Allow navigating from artist directly to songs via AS.xml setting

[the-black-eagle]

Description

As per the title, this allows users to skip navigating to albums from artists and goes directly to all the songs for an artist.
This works for any list of artists, so navigating via role -> composer -> artist -> songs also skips albums.

Motivation and context

Was requested or at least suggested on the forum https://forum.kodi.tv/showthread.php?tid=375313 by a team member. I can see how this is useful in some situations and at some point I think it's a candidate for the context menu, but not at the moment as that would be too invasive at this point.

How has this been tested?

Added the appropriate AS.xml setting and navigated through several screens of artists , composers, lyricists etc and in all cases, skipped the album node and navigated directly to songs.

What is the effect on users?

Users can choose to navigate from an artist directly to a list of songs, skipping the album / disc parts. This has to be enabled via AS.xml. Other navigation paths (album, boxsets, top 100 etc) are not affected by this.

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)
• Student submission (PR was done for educational purposes and will be treated as such)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed