Move all byte slice mutators into their own functions and randomly pick
from a slice, rather than using a large switch statement. Additionally
tests are added for each mutator which, lightly, test that they are
working as intended.
Other type mutators are left as-is for a similar refactor in the future.
Change-Id: Ifd4447b885885b3cc068748f33cc5d1ea25af62f
Reviewed-on: https://go-review.googlesource.com/c/go/+/329089
Trust: Roland Shoemaker <roland@golang.org>
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Katie Hockman <katie@golang.org> Reviewed-by: Jay Conrod <jayconrod@google.com>