Implement input method v1 keyboard grabs

The protocol is rather ambiguous regarding what events should be sent.
So, we send only hardware key events.

Another corner case is that the client has no way to indicate what
version of wl_keyboard it supports. In order to avoid crashing clients,
the grab_keyboard request returns wl_keyboard objects of v1.
1 job for !217 with work/seat-grab in 8 minutes and 9 seconds (queued for 35 minutes and 22 seconds)
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passed linux kf5-qt5 qt5.15 #98270

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