Add a "where is this asset used" feature

[martyf]

An awesome feature for the Asset browser would be the ability to see where an Asset is being used/referenced.

Could be really useful for content authors to reverse lookup an Asset in case they need to make explicit changes to a file (or to see every case where it gets used)

[nunoc66]

Would love this as well. Really useful to see any assets that aren't being used at all, or like you said, to make changes to a file and make sure its relevant to all other use cases.