refactor(forms): refactor Validators.email() regexp for easier comp…

…arison with WHATWG version (#32961)

As mentioned in the previous commit, the regexp used by
`Validators.email()` is a slightly enhanced version of the
[WHATWG one](https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address).

This commit refactors the regexp (without changing its behavior) to make
it more closely match the format of WHATWG version, so that it is easier
for people to compare it against the WHATWG one and understand the
differences.

The main changes were:
- Changing the order of characters/character classes inside `[...]`;
  e.g. `[A-Za-z]` --> `[a-zA-Z]`
- Mark all groups as non-capturing (since we do not use the captured
  values); e.g. `(foo)` --> `(?:foo)`
  (This could theoretically also have a positive performance impact, but
  I suspect JavaScript engines are already optimizing away capturing
  groups when they are not used.)

PR Close #32961

packages/forms/src/validators.ts

@@ -88,7 +88,7 @@ export const NG_ASYNC_VALIDATORS =
  * See [this commit](https://github.com/angular/angular.js/commit/f3f5cf72e) for more details.
  */
 const EMAIL_REGEXP =
-    /^(?=.{1,254}$)(?=.{1,64}@)[-!#$%&'*+/0-9=?A-Z^_`a-z{|}~]+(\.[-!#$%&'*+/0-9=?A-Z^_`a-z{|}~]+)*@[A-Za-z0-9]([A-Za-z0-9-]{0,61}[A-Za-z0-9])?(\.[A-Za-z0-9]([A-Za-z0-9-]{0,61}[A-Za-z0-9])?)*$/;
+    /^(?=.{1,254}$)(?=.{1,64}@)[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)*@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/;
 
 /**
  * @description