Add deps install mode setting

[LightArrowsEXE]

Depends on https://github.com/Jaded-Encoding-Thaumaturgy/vs-tools/pull/139. Adds the option for users to decide whether plugins should be automatically installed if missing.

[LightArrowsEXE]

TODO: Double-check this actually sets the setting in dependency_register before any other plugin. If it always sets it after, there's zero point in having this. If it doesn't, figure out a way to ensure it does.