head-management: add brightness-info-v1 extension

wire/jay_head_ext_brightness_info_v1.txt

@@ -0,0 +1,15 @@
+request destroy (destructor) {
+
+}
+
+event implied_default_brightness {
+    lux: u32,
+}
+
+event default_brightness {
+
+}
+
+event brightness {
+    lux: u32,
+}

wire/jay_head_manager_ext_brightness_info_v1.txt

@@ -0,0 +1,7 @@
+request destroy (destructor) {
+
+}
+
+event head {
+    head: id(jay_head_ext_brightness_info_v1) (new),
+}