RDMA/core: Promote UMEM to a core component

RDMA/core: Promote UMEM to a core component

To manage UMEM objects at the core level and reuse the existing
ib_destroy_cq*() flow, move the UMEM files to be built together with
ib_core. Attempting to call ib_umem_release() from verbs.c currently
results in the following error:

    depmod: ERROR: Cycle detected: ib_core -> ib_uverbs -> ib_core
    depmod: ERROR: Found 2 modules in dependency cycles!
    verbs.c:(.text+0x250c): undefined reference to `ib_umem_release'

Link: https://patch.msgid.link/20260213-refactor-umem-v1-4-f3be85847922@nvidia.com
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>