Add support for the input-timestamps protocol

[emersion]

wlroots events currently have a uint32_t time_msec field. It will be necessary to either change the field (struct timespec?) or add a new one (uint32_t time_nsec?).

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wlroots has migrated to gitlab.freedesktop.org. This issue has been moved to:

https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/1514

[ddevault]

Would prefer to add a new one