Break ml-config.xml into small parts (by default)

[grtjn]

Roxy already supports multiple config files, and rewrite-config in setup.xqy takes care of glueing together (if needed). Next step: break ml-config in small pieces, and in a dir structure. Read config files dynamically..

[grtjn]

Idea:

• allow pointing to a dir with ml.config.file (potential default deploy/ml-config/?)
• roxy grabs all files, regardless of dir/path, reads all, passes through as sequence to setup.xqy (already possible?)
• setup.xqy rewrite-config should be changed to expect pieces without wrappers

Bonus:

• investigate using Management REST api XML format..

[grtjn]

Mostly there, including splitting ml-config.xml into parts, but there are some questions:

• Migrate to using parts at new or init, or hold off on that for now?
• How handle upgrade from project using ml-config.xml?
• I think we need a different way of handling xml placeholders (such as: @ml.test-modules-db-xml)

[grtjn]

I think it is also worth taking a look at #692 and #704..

[grtjn]

Also look at #474..

[grtjn]

I think it would be nice if a user could just split/export the config in the new format with a command. Maybe ./ml local export config --format=ml-config-parts --target=deploy/ml-config/?