hw/block/nvme: refactor zone resource management

Zone transition handling and resource management is open coded (and
semi-duplicated in the case of open, close and finish).

In preparation for Simple Copy command support (which also needs to open
zones for writing), consolidate into a set of 'nvme_zrm' functions and
in the process fix a bug with the controller not closing an open zone to
allow another zone to be explicitly opened.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>