chore: Migrate ESLint configuration file to new flat format. (#8675)

* chore: rename .eslintrc.js to eslint.config.js

* chore: Rename eslint.config.js to eslint.config.mjs.

* refactor: Migrate ESLint config to new flat format.

* chore: Remove old per-directory and global ignore ESLint config files.

* fix: Allowlist JSDoc tag aliases.

* fix: Don't require @license in tests/*.

* fix: Add NodeJS globals to several files that run under Node.

* chore: Remove now-unneeded ESLint directives in core.

* chore: Remove invalid/unneeded ESLint directives.

* fix: Fix invalid use of `await` outside of an `async` function.

* fix: Improve screenshot error message.

* fix: Update ESLint config file to not warn on existing violations.

* chore: Remove suppressions of rules that weren't triggering.

* chore: Fix package-lock.json.

scripts/helpers.js

@@ -35,7 +35,7 @@ function posixPath(target) {
  * @return {string} The value s as a eval-able string literal.
  */
 function quote(str) {
-  /* eslint-disable no-control-regex, no-multi-spaces */
+  /* eslint-disable no-control-regex */
   /** Regexp for characters to be escaped in a single-quoted string. */
   const singleRE = /[\x00-\x1f\\\u2028\u2029']/g;
 
@@ -63,7 +63,7 @@ function quote(str) {
     '\u2028': '\\u2028',
     '\u2029': '\\u2029',
   };
-  /* eslint-enable no-control-regex, no-multi-spaces */
+  /* eslint-enable no-control-regex */
 
   return "'" + str.replace(singleRE, (c) => replacements[c]) + "'";
 }