Diff Patching with obb

[ComputerElite]

Beat Saber now has obbs and apks. Diff patching will need to be updated to work with both obbs and apks. Possible ways:

1. Concat apk and obb bytes (ordered by file name alphabetically), diff that, have a list of bytes indecies where to split the apk again
2. Have different diffs for apk and obb

I prefer the first one because it will be easier to implement most likely. However downgrading will need scroped storage access which afaik was fixed again by Oculus? Would need someone to validate that tho. So if you know lmk here.

ToDo:

• [x] Let user download created diff entries via browser
• [x] Let user upload apk and obbs as backup onto quest for diff generation
• [x] Put diff generation on background thread
• [ ] Create progress report for diff generation
• [x] Create create diff endpoint

[ComputerElite]

Doing first one. I'll probably add diffing functionality to QAVS

[ComputerElite]

switched to providing individual diff files per file as it was easier to implement

[ComputerElite]

Added in 1.15.20