Running eslint with --fix didn't fix many of the issues. The majority here had to be fixed by hand but a significant majority of the issues were related to a few files that I was able to use find-and-replace with. I regret not making this in to separate commits of the hand-fixes and the fixes from --fix but I don't recall --fix fixing any of the issues.
MozReview-Commit-ID: ANyg2qfo3Qx
In a following patch, all DevTools moz.build files will use DevToolsModules to
install JS modules at a path that corresponds directly to their source tree
location. Here we rewrite all require and import calls to match the new
location that these files are installed to.