Bug 1750933 - Add testing infrastructure for OPFS; r=dom-storage-reviewers,jari

.eslintrc.js

dom/fs/moz.build

dom/fs/test/common/.eslintrc.js

dom/fs/test/common/nsresult.js

dom/fs/test/common/test_basics.js

dom/fs/test/mochitest/head.js

dom/fs/test/mochitest/mochitest.ini

dom/fs/test/mochitest/test_basics.html

dom/fs/test/mochitest/test_basics_worker.html

dom/fs/test/mochitest/worker/.eslintrc.js

dom/fs/test/mochitest/worker/head.js

dom/fs/test/mochitest/worker/test_basics_worker.js

dom/fs/test/moz.build

dom/fs/test/xpcshell/head.js

dom/fs/test/xpcshell/test_basics.js

dom/fs/test/xpcshell/xpcshell.ini

dom/localstorage/ActorsParent.cpp

dom/quota/test/modules/content/.eslintrc.js

dom/quota/test/modules/content/Assert.js

dom/quota/test/modules/content/ModuleLoader.js