Migrate to import.meta.env and clean up types and eslint (#36362)

`import.meta.env` is supported in both vitest and webpack [as of
recent](https://github.com/webpack/webpack/pull/19996), so replace all
previous use of `process.env` with it. Current usage is limited to test
files, I've also verified it works in actual frontend code.

`webpack/module` is added to typescript types which includes the
definition for `import.meta.env`. I've also made the eslint globals more
precise. Finally, `__webpack_public_path__` is removed from our type
definitions because `webpack/module` also provides it.

web_src/js/webcomponents/absolute-date.test.ts

@@ -18,9 +18,9 @@ test('toAbsoluteLocaleDate', () => {
   expect(toAbsoluteLocaleDate('10000-01-01', '', {})).toEqual('Invalid Date');
 
   // test different timezone
-  const oldTZ = process.env.TZ;
-  process.env.TZ = 'America/New_York';
+  const oldTZ = import.meta.env.TZ;
+  import.meta.env.TZ = 'America/New_York';
   expect(new Date('2024-03-15').toLocaleString('en-US')).toEqual('3/14/2024, 8:00:00 PM');
   expect(toAbsoluteLocaleDate('2024-03-15', 'en-US')).toEqual('3/15/2024, 12:00:00 AM');
-  process.env.TZ = oldTZ;
+  import.meta.env.TZ = oldTZ;
 });