turnip: improve dirty bit handling a bit

turnip: improve dirty bit handling a bit

This moves some logic out of bind_draw_states, moving towards the eventual
goal of doing very little in bind_draw_states.

Split this out as a separate patch to make the DIRTY_INPUT_ATTACHMENTS more
visible: it can be safely removed because pipelines are subpass specific,
so there will always be a pipeline change to go with the CmdBeginRenderPass
and CmdNextSubpass (the CmdBindPipeline may not be in the subpass, but the
draw that flushes the pipeline update will be).

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5446>