Introduce new CSAL ftl bdev

[MaisenbacherD]

For this PR to be merged the PR openebs/spdk-rs#67
for spdk-rs needs to be resolved and the submodule reference must be
updated accordingly. :)

The SPDK ftl bdev allows to create a layered device with a (fast) cache
device for buffering writes that get eventually flushed out sequentially
to a base device. SDPK ftl is also known as the Cloud Storage
Acceleration Layer (CSAL).

This kind of device potentially enables the use of emerging storage
interfaces like Zoned Namespace (ZNS) or Flexible Data Placement (FDP)
capable NVMe devices. Up to this point, those NVMe command sets are not
yet supported in SPDK upstream. However, the acceleration aspect of a
fast cache device already adds value.
With future support of new devices for SDPK ftl, Mayastor would already
be capable of utilizing those features simply by upgrading SDPK.

For now, the ftl_mount_fs test cases are hidden behind the ignore
attribute because PCIe devices are required for this test until
SPDK v24.09 is picked up, which introduces variable sector size emulation
for ftl devices.
To run these tests use the following:

RUST_LOG=TRACE cargo test -- --test-threads 1 --test ftl_mount_fs --nocapture --ignored

This patch introduces a new ftl device uri scheme:

ftl:///<ftl-device-name>?bbdev=<dev-uri-nested-encoding>&cbdev=<dev-uri-nested-encoding>

<dev-uri-nested-encoding> can be any already valid device uri where '?'
are replaced with '!' and '&' are replaced with '|'.
With SPDK v24.05 only PCIe devices will work where the cache device is
formatted to 4KiB+64B LBA format and the base device to 4KiB LBA format.

From SPDK v24.09 on, any device with a block size of 4KiB will work for
both cache and base device.

CSAL paper reference:
https://dl.acm.org/doi/10.1145/3627703.3629566

[MaisenbacherD]

Discussion question: The spdk_ftl_conf allows us to set configurations like core_mask and l2p_dram_limit. Are those configurations worth exposing through the ftl uri, or should we go with the default configuration?