Add a function for returning the appropriate "no access" API error code.

Review Request #5671 — Created April 2, 2014 and submitted — Latest diff uploaded

Information

Djblets
master
062352f...

Reviewers

We had several places in WebAPIResource that calculated the proper error
code to use for indicating that access isn't allowed for a resource.
Consumers then had to repeat that logic, which was silly and pointless.

This introduces a function, get_no_access_error(), that performs the
calculation.

Unit tests in Djblets and RB pass.