Reduce utils.Cfg references (#7650)

* app.UpdateConfig method

* test fix

* another test fix

* the config override option as-was is just error prone, remove it for now

* derp

api4/file.go

@@ -58,17 +58,17 @@ func (api *API) InitFile() {
 }
 
 func uploadFile(c *Context, w http.ResponseWriter, r *http.Request) {
-	if !*utils.Cfg.FileSettings.EnableFileAttachments {
+	if !*c.App.Config().FileSettings.EnableFileAttachments {
 		c.Err = model.NewAppError("uploadFile", "api.file.attachments.disabled.app_error", nil, "", http.StatusNotImplemented)
 		return
 	}
 
-	if r.ContentLength > *utils.Cfg.FileSettings.MaxFileSize {
+	if r.ContentLength > *c.App.Config().FileSettings.MaxFileSize {
 		c.Err = model.NewAppError("uploadFile", "api.file.upload_file.too_large.app_error", nil, "", http.StatusRequestEntityTooLarge)
 		return
 	}
 
-	if err := r.ParseMultipartForm(*utils.Cfg.FileSettings.MaxFileSize); err != nil {
+	if err := r.ParseMultipartForm(*c.App.Config().FileSettings.MaxFileSize); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
@@ -179,7 +179,7 @@ func getFileLink(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if !utils.Cfg.FileSettings.EnablePublicLink {
+	if !c.App.Config().FileSettings.EnablePublicLink {
 		c.Err = model.NewAppError("getPublicLink", "api.file.get_public_link.disabled.app_error", nil, "", http.StatusNotImplemented)
 		return
 	}
@@ -269,7 +269,7 @@ func getPublicFile(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if !utils.Cfg.FileSettings.EnablePublicLink {
+	if !c.App.Config().FileSettings.EnablePublicLink {
 		c.Err = model.NewAppError("getPublicFile", "api.file.get_public_link.disabled.app_error", nil, "", http.StatusNotImplemented)
 		return
 	}
@@ -288,7 +288,7 @@ func getPublicFile(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if hash != app.GeneratePublicLinkHash(info.Id, *utils.Cfg.FileSettings.PublicLinkSalt) {
+	if hash != app.GeneratePublicLinkHash(info.Id, *c.App.Config().FileSettings.PublicLinkSalt) {
 		c.Err = model.NewAppError("getPublicFile", "api.file.get_file.public_invalid.app_error", nil, "", http.StatusBadRequest)
 		http.Redirect(w, r, c.GetSiteURLHeader()+"/error?message="+utils.T(c.Err.Message), http.StatusTemporaryRedirect)
 		return