PLT-8131 (part2) Add plugin key value store support (#7902)

* Add plugin key value store support

* Add localization strings

* Updates per feedback

store/store.go

@@ -63,6 +63,7 @@ type Store interface {
 	Reaction() ReactionStore
 	Job() JobStore
 	UserAccessToken() UserAccessTokenStore
+	Plugin() PluginStore
 	MarkSystemRanUnitTests()
 	Close()
 	DropAllTables()
@@ -440,3 +441,9 @@ type UserAccessTokenStore interface {
 	UpdateTokenEnable(tokenId string) StoreChannel
 	UpdateTokenDisable(tokenId string) StoreChannel
 }
+
+type PluginStore interface {
+	SaveOrUpdate(keyVal *model.PluginKeyValue) StoreChannel
+	Get(pluginId, key string) StoreChannel
+	Delete(pluginId, key string) StoreChannel
+}