MM-16821 - Add a KVCompareAndDelete to the plugin API (#11804)

* Implement KVCompareAndDelete and KVCompareAndDeleteJSON

* Add tests for KVCompareAndDelete

* Update minimum server version

* Handle nil value on CompareAndSet so that it deletes it

* Fix comments

* Tweaks from PR comments

* Go back to deleted, err

store/storetest/mocks/PluginStore.go

@@ -12,6 +12,29 @@ type PluginStore struct {
 	mock.Mock
 }
 
+// CompareAndDelete provides a mock function with given fields: keyVal, oldValue
+func (_m *PluginStore) CompareAndDelete(keyVal *model.PluginKeyValue, oldValue []byte) (bool, *model.AppError) {
+	ret := _m.Called(keyVal, oldValue)
+
+	var r0 bool
+	if rf, ok := ret.Get(0).(func(*model.PluginKeyValue, []byte) bool); ok {
+		r0 = rf(keyVal, oldValue)
+	} else {
+		r0 = ret.Get(0).(bool)
+	}
+
+	var r1 *model.AppError
+	if rf, ok := ret.Get(1).(func(*model.PluginKeyValue, []byte) *model.AppError); ok {
+		r1 = rf(keyVal, oldValue)
+	} else {
+		if ret.Get(1) != nil {
+			r1 = ret.Get(1).(*model.AppError)
+		}
+	}
+
+	return r0, r1
+}
+
 // CompareAndSet provides a mock function with given fields: keyVal, oldValue
 func (_m *PluginStore) CompareAndSet(keyVal *model.PluginKeyValue, oldValue []byte) (bool, *model.AppError) {
 	ret := _m.Called(keyVal, oldValue)