[ftr] Create v2.0.0 endpoints

[daniel-jettka]

Is your feature request related to a problem? Please describe.
Make API more flexible and usable (not use xql as endpoints, but nice URLs)

Describe the solution you'd like

• create endpoint for every output
• move functions from xql to xqm (keep old xql endpoints, i.e. API v1.0.0 available)
• use JSON API format
• update to XQuery to v3.1

Describe alternatives you've considered
./.

Additional context
./.