PLT-4938 Add app package and move logic over from api package (#4931)

* Add app package and move logic over from api package

* Change app package functions to return errors

* Move non-api tests into app package

* Fix merge

api/emoji_test.go

@@ -13,6 +13,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/mattermost/platform/app"
 	"github.com/mattermost/platform/model"
 	"github.com/mattermost/platform/store"
 	"github.com/mattermost/platform/utils"
@@ -44,11 +45,11 @@ func TestGetEmoji(t *testing.T) {
 	}
 
 	for i, emoji := range emojis {
-		emojis[i] = store.Must(Srv.Store.Emoji().Save(emoji)).(*model.Emoji)
+		emojis[i] = store.Must(app.Srv.Store.Emoji().Save(emoji)).(*model.Emoji)
 	}
 	defer func() {
 		for _, emoji := range emojis {
-			store.Must(Srv.Store.Emoji().Delete(emoji.Id, time.Now().Unix()))
+			store.Must(app.Srv.Store.Emoji().Delete(emoji.Id, time.Now().Unix()))
 		}
 	}()
 
@@ -76,7 +77,7 @@ func TestGetEmoji(t *testing.T) {
 		Name:      model.NewId(),
 		DeleteAt:  1,
 	}
-	deleted = store.Must(Srv.Store.Emoji().Save(deleted)).(*model.Emoji)
+	deleted = store.Must(app.Srv.Store.Emoji().Save(deleted)).(*model.Emoji)
 
 	if returnedEmojis, err := Client.ListEmoji(); err != nil {
 		t.Fatal(err)
@@ -314,10 +315,10 @@ func createTestPng(t *testing.T, width int, height int) []byte {
 }
 
 func createTestEmoji(t *testing.T, emoji *model.Emoji, imageData []byte) *model.Emoji {
-	emoji = store.Must(Srv.Store.Emoji().Save(emoji)).(*model.Emoji)
+	emoji = store.Must(app.Srv.Store.Emoji().Save(emoji)).(*model.Emoji)
 
 	if err := WriteFile(imageData, "emoji/"+emoji.Id+"/image"); err != nil {
-		store.Must(Srv.Store.Emoji().Delete(emoji.Id, time.Now().Unix()))
+		store.Must(app.Srv.Store.Emoji().Delete(emoji.Id, time.Now().Unix()))
 		t.Fatalf("failed to write image: %v", err.Error())
 	}