Set up location restriction message/allow pdf viewer to authorize location restriction

[hudajkhan]

Closes #2360

What this pull request does:

• Adds location restriction methods to pdf viewer: does the purl object have a location restriction, and what is the location
• Sets up a component to display the location restriction message based on a given location code
• Displays the location restriction component in the PDF component display if the object has a location restriction
• If the iiif auth (in file_auth_controller) returns an access denied message AND the file in question is the first file (i.e. the file which will have the render viewer method called and the PDF displayed in the screen), then an auth denied event is dispatched which will trigger the locked icon in the screen.
• Allows an item that is restricted by location to be visible to a user at that location (i.e. when the authorization process returns success)
• Extends the viewer.available function to also include location restricted cases, so the above scenario is now possible whereas before any location restricted case would immediately display the content not available method
• Fixes a bug in the fallback message method which was needed a return statement

What this pull request does not do:
Check the authorization of files other than the first one to be rendered. This issue can address that separately: #2651