Split common code out of {Get,Put}LfsGlobalConfig

Both GetLfsGlobalConfig and PutGlobalConfig classes perform the
same checks that the user is an administrator and that the project
is All-Projects.

Split these checks out to a class to reduce duplicated code, and so
it can be reused in other classes later.

Remove the call to asIdentifiedUser. This is redundant as the call
to testOrFalse(...) will return false anyway if the user is not
logged in.

Change-Id: Ib601a8cad28becd717fecd4db63ee8206934a46a
3 files changed