protocol: add wl_output.{name,description}

This is inspired from xdg-output-unstable-v1. This allows clients to
get the name and description without having to use xdg_output. This
should eventually allow us to restrict xdg_output to clients like
Xwayland.

The name is a unique non-persistent user-friendly string that can be
used to refer to an output. This can be used by Wayland clients to
refer to a specific wl_output (e.g. across processes or in CLI
arguments).

The description is a non-unique user-friendly string that can be
displayed to the user.

Signed-off-by: Simon Ser <contact@emersion.fr>
References: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/issues/7

protocol/wayland.xml

@@ -2504,7 +2504,7 @@
     </event>
   </interface>
 
-  <interface name="wl_output" version="3">
+  <interface name="wl_output" version="4">
     <description summary="compositor output region">
       An output describes part of the compositor geometry.  The
       compositor works in the 'compositor coordinate system' and an
@@ -2568,7 +2568,7 @@
 	implementing a desktop-style output layout or those exposing virtual
 	outputs, might fake this information. Instead of using x and y, clients
 	should use xdg_output.logical_position. Instead of using make and model,
-	clients should use xdg_output.name and xdg_output.description.
+	clients should use name and description.
       </description>
       <arg name="x" type="int"
 	   summary="x position within the global compositor space"/>
@@ -2687,6 +2687,62 @@
 	use the output object anymore.
       </description>
     </request>
+
+    <!-- Version 4 additions -->
+
+    <event name="name" since="4">
+      <description summary="name of this output">
+	Many compositors will assign user-friendly names to their outputs, show
+	them to the user, allow the user to refer to an output, etc. The client
+	may wish to know this name as well to offer the user similar behaviors.
+
+	The name is a UTF-8 string with no convention defined for its contents.
+	Each name is unique among all wl_output globals. The name is only
+	guaranteed to be unique for the compositor instance.
+
+	The same output name is used for all clients for a given wl_output
+	global. Thus, the name can be shared across processes to refer to a
+	specific wl_output global.
+
+	The name is not guaranteed to be persistent across sessions, thus cannot
+	be used to reliably identify an output in e.g. configuration files.
+
+	Examples of names include 'HDMI-A-1', 'WL-1', 'X11-1', etc. However, do
+	not assume that the name is a reflection of an underlying DRM connector,
+	X11 connection, etc.
+
+	The name event is sent after binding the output object. This event is
+	only sent once per output object, and the name does not change over the
+	lifetime of the wl_output global.
+
+	Compositors may re-use the same output name if the wl_output global is
+	destroyed and re-created later. Compositors should avoid re-using the
+	same name if possible.
+
+	The name event will be followed by a done event.
+      </description>
+      <arg name="name" type="string" summary="output name"/>
+    </event>
+
+    <event name="description" since="4">
+      <description summary="human-readable description of this output">
+	Many compositors can produce human-readable descriptions of their
+	outputs. The client may wish to know this description as well, e.g. for
+	output selection purposes.
+
+	The description is a UTF-8 string with no convention defined for its
+	contents. The description is not guaranteed to be unique among all
+	wl_output globals. Examples might include 'Foocorp 11" Display' or
+	'Virtual X11 output via :1'.
+
+	The description event is sent after binding the output object and
+	whenever the description changes. The description is optional, and may
+	not be sent at all.
+
+	The description event will be followed by a done event.
+      </description>
+      <arg name="description" type="string" summary="output description"/>
+    </event>
   </interface>
 
   <interface name="wl_region" version="1">