Fix hmr updates with rebuilding for build errors (#60676)
### What
Sometimes the display of the error overlay is not consistent even when
you fixed the error
Example:
* You have a client page, and you add metadata export, Next.js will
error that it's not allowed in client component.
* You fix it, but the error overlay is not disappeared. Or you fix it,
then introduce it again, then fix it again, the error overlay is still
there.
### How
We're checking if the HMR webpack hash is changed to decide if we're
going to do a hot update in `BUILT` and `SYNC` event, but we update the
hash at the very beginning of the event handler. `isUpdateAvailable()`
will return `false` in the later calls but the hash has already changed
before. So we check if they change before applying hot updates, and then
use it later with `isUpdateAvailable()` to determine if necessary to
process a new hot update
Closes NEXT-2107
---------
Co-authored-by: Tim Neutkens <tim@timneutkens.nl>
