Show errors from URL parser

[peckato1]

In case somebody requests URLs like /restconf/ds/ietf-datastores:running/ we respond with invalid syntax error. I think that RFC 8040 + RFC 8527 say that there should not be the terminating slash.

Anyway, we should report what was wrong and not just "invalid syntax". Take a look at error handling and implemenent something prettier than just reporting true/false from the URL parser

[peckato1]

Okay, the problem is a bit different. If we issue

$ curl --http2-prior-knowledge -X PATCH [::1]:10080/restconf/ds/ietf-datastores:running/ -H "content-type: application/yang-patch+json" --data @some_yang_patch.json

the URL parses just fine, the problem is in the invocation of asLibyangPathSplit from YANG patch handling, because it gets called with uriPath parameter /restconf/ds/ietf-datastores:running//czechlight-roadm-device:mc. The double slashes is obviously a bug.

I will try to fix that and also add more helpful parser error reports.