[Feature] Stash endpoints for all item types

[Valkyr-JS]

Is your feature request related to a problem? Please describe.
I'm working on a pipeline for curating my data, which includes a number of Stash instances referencing each other via endpoints. This works well for scenes, studios and performers, but cannot be done for any other data types.

Describe the solution you'd like
Stash endpoints should be able to be set on all, or at least most, data types. Images and galleries would benefit as much as scenes do. Endpoints could make tags easier to manage in databases with multiple Stash boxes where tag names and descriptions may conflict. That leaves groups and markers, which also could benefit. Allowing endpoints for all data types may encourage third-party development of scrapers or even stash boxes to cater to that data, e.g. as mentioned here.

Describe alternatives you've considered
For my own pipelines usage - which I appreciate is a unique user issue more than a wider community one - I have tried using aliases or performer disambiguations to store unique IDs related to the endpoint I'm referencing. This isn't an ideal solution.