zink: add a second descriptor manager

zink: add a second descriptor manager

this is the "lazy" descriptor manager, which aims to perform the least
amount of work calculating updates while ignoring the overhead that an
update may incur: effectively the inverse of the caching manager

in this initial implementation, divergence exists between the descriptor
layouts of the cached manager and the lazy manager in order to avoid
incurring regressions in the existing descriptor architecture; this will
be reconciled in a followup MR that refactors and unifies descriptor layouts

during this interim period and until such reconciliation occurs,
the default descriptor manager is now the lazy manager for testing purposes as
there are no changes here which can affect the existing infrastructure

the caching descriptor manager can be selected with the ZINK_CACHE_DESCRIPTORS
env var and will be automatically used for vulkan drivers which don't support
the features required for lazy mode (templates)

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11093>