Add MirrorInterval to the API (#14163)

* Added MirrorInterval to the API

* Remove MirrorInterval from CreateRepository

* Removed Duplicate UpdateMirror Function

* Updated Error Logging

* Update Log Message for is not Mirror

Co-authored-by: 6543 <6543@obermui.de>

* Delete Debug Statement that snuck in

Co-authored-by: zeripath <art27@cantab.net>

* Add Check for If Interval is too small

* Output to API Call

* Add Error Object when time is Less than Min Interval

* Frequency Error Message

Co-authored-by: zeripath <art27@cantab.net>

* Allow Zero Mirror Interval

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: zeripath <art27@cantab.net>

models/repo.go

@@ -979,6 +979,7 @@ type CreateRepoOptions struct {
 	AutoInit       bool
 	Status         RepositoryStatus
 	TrustModel     TrustModelType
+	MirrorInterval string
 }
 
 // GetRepoInitFile returns repository init files