Add improved Local Site limiting to IntegrationConfigForm.
Review Request #10418 — Created Feb. 18, 2019 and submitted
IntegrationConfigFormnow makes use of
in order to gain more comprehensive support for Local Site limiting.
Now, any subclass of this form will automatically have any of its model
relationship or condition fields bound and validated to a Local Site.
This replaces the very limited support the form natively had before.
Unit tests pass.
Used this with Local Site limiting and verified that everything was
properly filtered and validated against the Local Site.