Fix EZP-20822: API services phpdoc and input validation

This PR fixes issue https://jira.ez.no/browse/EZP-20822

Ids type needs to be ```mixed``` and not ```int``` since NoSQL storage will use hashes as ids.
Also on quite few places ```is_numeric``` was used to validate arguments and VO properties, which is obviously wrong.

For easier review changes to service interfaces are in separate commit.

Additional:
* fixed small CS issue
* fixed small PHPDoc errors
* fixed updating ```Role``` with the same identifier throwing an exception