Add more eg refactoring templates

[jbduncan]

We use eg to auto-fix certain classes of bugs, but we can do more.

If help with eg is needed, refer to https://rakyll.org/eg/.

• [ ] time package
  • [ ] == to Equal (even if revive catches this, being able to auto-fix it is valuable)
• [ ] bool expression simplifications
  • [ ] !(a >= b) to a < b
  • [ ] !(a > b) to a <= b
  • [ ] !(a <= b) to a > b
  • [ ] !(a < b) to a >= b
  • [ ] !(a != b) to a == b
  • [ ] !(a == b) to a != b
  • [ ] !!a to a
• [ ] string == "" or string == `</code> tolen(string) == 0`
• [ ] Examples in https://errorprone.info/docs/refaster
• [ ] Examples in https://github.com/PicnicSupermarket/error-prone-support
• [ ] Any other examples that revive can catch but can't auto-fix

[jbduncan]

eg may be replaced with ast-grep once #27 is done.