js,gg: more work on porting gg to JS backend (#12903)

vlib/gx/color.v

@@ -232,3 +232,7 @@ const (
 pub fn color_from_string(s string) Color {
 	return gx.string_colors[s]
 }
+
+pub fn (c Color) to_css_string() string {
+	return 'rgb($c.r,$c.g,$c.b)'
+}

vlib/gx/text.js.v

@@ -0,0 +1,14 @@
+module gx
+
+pub enum HorizontalAlign {
+	left
+	center
+	right
+}
+
+pub enum VerticalAlign {
+	top
+	middle
+	bottom
+	baseline
+}