Check of enable-http-data config option
HTTP/2 Return 400 bad request if no path match
Test: updated yang file revisions, extended restconf config with http-data
* `CLICON_RESTCONF_PATH` is now obsolete for sure
* Instead if you use fgci/nginx:
* Use `restconf/fcgi-socket`
* Ensure `<CLICON_FEATURE>clixon-restconf:fcgi</CLICON_FEATURE>` is set
* Added default values to restconf-config and save fcgi-socket-path in memory
* Removed obsolete options:
* `CLICON_YANG_LIST_CHECK`
* `CLICON_RESTCONF_PATH` (moved to restconf/fcgi-path)
* Fixed: Configure option `CLICON_RESTCONF_PRETTY` was marked as obsolete but was still used.
* `CLICON_RESTCONF_PRETTY` is now obsolete for sure
* Instead restconf/pretty is used with API function restconf_pretty_get()
* Not backward compatible: All uses of the ca-auth callback in restconf plugins must be changed
* New version is: `int ca_auth(h, req, auth_type, authp, userp)`
* where `auth_type` is the requested authentication-type (none, client-cert or user-defined)
* `authp` is the returned authentication flag
* `userp` is the returned associated authenticated user
* and the return value is three-valued: -1: Error, 0: ignored, 1: OK
* For more info see [clixon-docs](https://clixon-docs.readthedocs.io/en/latest/restconf.html)
* New clixon-restconf@2020-12-30.yang revision
