Add handler access check to mc_issue_add()

The mc_issue_add() API was missing a check to validate that specified handler has the appropriate access level.

Fixes #16993
Add handler access check to mc_issue_update()

The mc_issue_update() wasn't check if the handler has access level to handle issues.
Add can assign check to mc_issue_add()

Users who report an issue with handler set must have the access level required to assign issues.

Issue #16993
Add access check to mc_issue_get() for handler_id

Disclose the handler id only if the user has the appropriate access level to see such information.

Issue #16993
Refactor handler access check for soap api

Move the check to a shared method used by mc_issue_add() and mc_issue_update().

Issue #16993
Propagate access check soap faults to caller

Now that access check is done in its own function, the caller need to propagate the soap faults since we are not using real exceptions (unfortunately!).
Merge branch 'Issue16993_SoapHandlerCheck'