Create ext-image-capture-source-v1 and ext-image-copy-capture-v1

This is a new screencopy protocol which improves upon wlr-screencopy-unstable-v1.

Supersedes: !39 (closed)

• Review
• 2 ACKs
  • wlroots (@emersion)
  • COSMIC (@Drakulix)
• 2 implementations
  • wlroots: wlroots/wlroots!4545 (merged)
  • wayvnc: https://github.com/any1/wayvnc/tree/ext-screencopy-v1
  • grim: https://git.sr.ht/~emersion/grim/log/ext-screencopy-v1

stable/linux-dmabuf/linux-dmabuf-v1.xml

@@ -378,7 +378,7 @@
             of planes and the format, bad format, non-positive width or
             height, or bad offset or stride.
           - INVALID_WL_BUFFER, in case the cause for failure is unknown or
-            plaform specific.
+            platform specific.
         - the server creates an invalid wl_buffer, marks it as failed and
           sends a 'failed' event to the client. The result of using this
           invalid wl_buffer as an argument in any request by the client is