mgr/dashboard: update to angular v15

mgr/dashboard: update to angular v15

- The scss import was broken because of the ~ symbol. Looks like its not
needed.

- Login username/password label was somehow broken because of the
placeholder class and color. instead of applying the color through a
class I applied the color directly to the attribute and it worked

- Typescript 4.9 uses ES2022 and it complaints about using some items
  before its initialization. There were other typescript fixes need to
be delivered because of this change.

- Reverting back the badge to rectangular shape (because I feel like the
  round leaves out some empty spaces)

Fixes: https://tracker.ceph.com/issues/62844
Signed-off-by: Nizamudeen A <nia@redhat.com>
(cherry picked from commit 7f8f232da45721f669b313bb883af948c7a9cce1)