turnip: Save the renderpass's clear values in the cmdbuf state.

turnip: Save the renderpass's clear values in the cmdbuf state.

For delaying clears to subpass begin time, I needed to save these until
later.  Turns out this cleans up a good bit of threading these values all
through the command buffer setup.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20994>