[API] GET / SET User Settings (#16169)

* API: GET/SET User Settings

* linter

* Apply suggestions from code review

* Update modules/structs/user.go

* lint

* fix swagger

* move User2UserSettings to convert

* as per @zeripath "preferences" -> "settings"

Co-authored-by: techknowlogick <matti@mdranta.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

routers/api/v1/swagger/options.go

@@ -161,4 +161,7 @@ type swaggerParameterBodies struct {
 
 	// in:body
 	CreateTagOption api.CreateTagOption
+
+	// in:body
+	UserSettingsOptions api.UserSettingsOptions
 }

routers/api/v1/swagger/user.go

@@ -42,3 +42,10 @@ type swaggerResponseUserHeatmapData struct {
 	// in:body
 	Body []models.UserHeatmapData `json:"body"`
 }
+
+// UserSettings
+// swagger:response UserSettings
+type swaggerResponseUserSettings struct {
+	// in:body
+	Body []api.UserSettings `json:"body"`
+}