[Feat] Improvements to importing games

[CommandMC]

• Legendary will now archive the manifest for every game in its install folder and use it to recover install state on import
  • Most of this was already implemented, although some changes had to be made to no longer delete GUIDs (used for the file name of the archived manifest and metadata file)
  • This will probably break EGL sync a bit, since the code seems to assume that "Game has GUID" = "Game comes from EGL"
• It's possible to specify install tags on import
  • These aren't used during the import yet, but the only artifact of that should be an erroneous "Some files are missing from the game installation" message