Change direct access to Common.UserConfig to a getter

This will allow us to turn the field into an atomic.Value for safe concurrent
access.

pkg/common/common.go

@@ -11,10 +11,18 @@ import (
 type Common struct {
 	Log        *logrus.Entry
 	Tr         *i18n.TranslationSet
-	UserConfig *config.UserConfig
+	userConfig *config.UserConfig
 	AppState   *config.AppState
 	Debug      bool
 	// for interacting with the filesystem. We use afero rather than the default
 	// `os` package for the sake of mocking the filesystem in tests
 	Fs afero.Fs
 }
+
+func (c *Common) UserConfig() *config.UserConfig {
+	return c.userConfig
+}
+
+func (c *Common) SetUserConfig(userConfig *config.UserConfig) {
+	c.userConfig = userConfig
+}