[IDEA] Collections: create views on the library, a way to manage large libraries

[Tim Curtis]

FYI: The implementation can prolly be done within the existing Library search/filtering code as described below. It does not involve any PHP template screens (we don't want those) or overwriting the libcache_all.json file and it maintains full Library functionality on any particular View.

- Enhance existing search/filtering code and modal to allow/parse the "OR" operator
- Add ability to save searches as named items (Views) i.e., libcache_"viewname".json
- Add SQL table for maintaining View names and associated search criteria
- Add modal for listing all saved Views for Select/Edit/Refresh/Remove
- Add "Custom Views" to Library menu like below

Radio
Folder
Tag
Album
------
All Music
Recently Added
Custom Views

I won't be able to scope this out until moOde 8 series (Q1 2022) and we are not planning to make any changes to the existing 7 series codebase due to workload on a new development workflow and build system for 8 series.

At some point I'll post a moOde 8 status thread and report whats going to be in the initial release.

-Tim