Split Loaded/Standby section into two separate sections

[lqnrd]

Description

I really like the idea introduced in January to have "Standby" as a third state of displays. There were quite a lot of displays lost somewhere at the bottom of the list.

One big drawback to having a combined "Loaded/Standby" section however, is that the top most section can get a little cluttered. I myself have a lot of displays for specific dungeon bosses (think mythic+), for raid bosses, for whole dungeons, or even for one particular world map. Most of these will almost never be loaded during a given session, but they are still taking up place at the top of the list. I won't delete them, because they will be used once or twice a week, and checking "never load" every time for each of these is just not feasable.

With this commit, we now have three different sections:

• Loaded: everything that's loaded and running right now (like always-on displays, health and mana bars, cast bars)
• Standby: everything that could be loaded (like encounter or dungeon specific stuff)
• Not loaded: everything that would never be loaded in the current session

If you really don't want to have this, you are still free to close this pull request, and if there's something I overlooked in the code, please let me know!

Fixes #4821

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested

The changes have been tested on the current version available on curse, which is 5.10.1.

• adding a new display, rename, drag and drop with groups, delete display again

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

[InfusOnWoW]

The linked ticket explains why the top section is the way it is. I want all potentially relevant auras to appear in the top section. That is err on the side of showing too many auras in that section.

Specifally, there has been quite a bit of user confusion on why auras don't show in the loaded section after importing before changing the categories. Introducing a standby section would reintroduce that problem. We recently made a small change where the groups get loaded/standby icons from their child auras.

Also at this time, I don't want to introduce any big changes to that display just after users have adjusted to the new categorization.