Apply/Ingest - Apply loadout experience Refinement

See #421 for details.

Refinements:

[x] Apply button is hidden until user makes a change to the loadout in the current App session.
- This is due to not having access to lastApplied loadout and last applied revision (see #871)
[x] Showing whether a different loadout is currently applying (same game installation)
[x] Launching the game shouldn't do an auto apply
- [x] Don't apply latest loadout, run at the old disk state and ingest the changes at that point and rebase uncommitted on top.
[ ] Disable the launch button when the current loadout isn't the active one
[ ] Button for seeing the file changes is missing.
[ ] View apply changes button should be updated https://www.figma.com/file/4Kt4QcSv8rACPpo3y4T4lr/%F0%9F%93%B1-Apply-loadout-changes?type=design&node-id=529%3A25645&mode=design&t=phYpwgO7e8CNDjag-1

[ ] Number of changes to Apply is missing
- This gets quite complicated when the last applied loadout is different from the currently selected loadout, since there is no number of revisions of difference between the two.
- This could be computed differently once we have event sourcing.
[ ] UI Styling for buttons and spinner doesn't match design.

Apply backend has a number of open issues tracked in Epic: #980 Some of the issues above require backend fixes from that epic