Extend default gem level functionality

[Lothrik]

Fixes #4630.

This replaces the old gem level selection and "match gem level to character" level options with a dropdown selection that has four options:

• Normal Maximum: All gems default to their highest valid non-corrupted gem level.
• Corrupted Maximum: Normal gems default to their highest valid corrupted gem level. Awakened gems default to their highest valid non-corrupted gem level.
• Awakened Maximum: All gems default to their highest valid corrupted gem level.
• Match Character Level: All gems default to their highest valid non-corrupted gem level that your character meets the level requirement for. This hides gems with a minimum level requirement above your character level, preventing them from showing up in the dropdown list.

Before screenshot:

After screenshot:

[Lothrik]

Merged #4761 to resolve conflicts.
Fixes #4759 #2830

[QuickStick123]

There is also the issue that it won't hide gems on load either I wasn't sure how to resolve this one though.

[QuickStick123]

The issue doesn't seem to be resolved and still uses normal gem level stuff when set to match character level and reload/load pob. Everything else seems to behave correctly.

[Lothrik]

@QuickStick123 That issue should be resolved. self:PopulateGemList() wasn't being called when sortCache was uninitialized, meaning the gem list was always incorrect on new/empty socket groups.

[Wires77]

The only issue I see with this is that those people who have selected "Match to character level" in old versions of PoB will have that selection overwritten to "Normal Maximum" instead.

[Lothrik]

@Wires77 33e22be should handle legacy build configuration settings properly.

[QuickStick123]

The only remaining issue I see with this is that it loses the functionality to say add level 15 gems if you want to make a early maps config or something similar easily.

[Wires77]

I think the early mapping use case is probably niche, and using default gem level then adding each gem individually again seems like a pain anyway, so hopefully we can teach people to copy/paste the endgame levels instead.