[Enhancement] Rename "Install Mods" to "Apply Changes" or something

Currently the wording is confusing. It makes me expect to only have to press it if I've chosen a mod to install, but you also need to press it when activating or deactivating mods, or using a local mod file. I'd think "Apply Changes" would be a better representation of what it actually does, and that you need to press it after doing these things.