Update imgix support to be more granular (disable CP transforms by volume)

[prescottcarr]

Is your feature request related to a problem? Please describe.

CP requests are forcing the use of imgix and causing thumbnails from other Volumes (not using imgix) to 404/no display in the CP.

Describe the solution you would like

It would be great if the integration of imgix could disable CP requests for certain transforms or be related to the Volume. For my example, I only use imgix for the 'Images' volume and it would be ideal if the CP would use imgix for these CP transforms (eg. User Photo Location) if the Volume is selected.

Additional context