Fix bogus RA tab artwork

I was really disappointed to see just how broken these were:

- Soviet tab coordinates were off by 1px in the texture atlas.
- Soviet-normal tab glyphs were off by 1px.
- Allied-selected tabs had random semi-transparent pixels.
- Most tabs had a discoloured pixel near the left edge.
- Added captured-tech tab versions for aircraft (wired up) and ships (not wired up).
- Removed multiple bitrotted source art versions (none of which had correct layers).

Fixes #5915.