protocol: add wl_output.{name,description}

This is taken 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 only difference is that the name character restriction is
lifted, to allow for potentially better output names, e.g. by using
some kind of generalized PATH KMS property [1].

[1]: https://lists.freedesktop.org/archives/dri-devel/2019-June/221902.html

Signed-off-by: Simon Ser <contact@emersion.fr>
References: wayland/wayland-protocols#7
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debian:buster@container-prep

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build-native-autotools

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passed #6846651
build-native-meson

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