mgr/dashboard: add snap schedule M, Y frequencies

Added M and Y (month and year) repeat frequencies to snap schedule
create form.

Fixes: https://tracker.ceph.com/issues/64614

Signed-off-by: Ivo Almeida <ialmeida@redhat.com>

src/pybind/mgr/dashboard/frontend/src/app/shared/enum/repeat-frequency.enum.ts

@@ -1,17 +1,23 @@
 export enum RepeatFrequency {
   Hourly = 'h',
   Daily = 'd',
-  Weekly = 'w'
+  Weekly = 'w',
+  Monthly = 'M',
+  Yearly = 'Y'
 }
 
 export enum RepeaFrequencySingular {
   h = 'hour',
   d = 'day',
-  w = 'week'
+  w = 'week',
+  M = 'month',
+  Y = 'year'
 }
 
 export enum RepeaFrequencyPlural {
   h = 'hours',
   d = 'days',
-  w = 'weeks'
+  w = 'weeks',
+  M = 'months',
+  Y = 'years'
 }