[multicast] wire up softnpu backend to multicast table ops

This wires up the softnpu ASIC backend to support multicast end-to-end by
translating DPD's sidecar.p4 table operations into sidecar-lite.p4's
simplified P4 pipeline.

## AsicMulticastOps

We replace the stubbed AsicMulticastOps implementation (which returned
"OperationUnsupported" for group creation and port addition with in-memory group
tracking via McGroupData, following the tofino_stub pattern.

Group membership is used by the table translation layer to build port
bitmaps for sidecar-lite's Replicate extern. Ports >= 128 are
rejected at add time to match sidecar-lite's 128-bit bitmap width.

## Table translation (asic/src/softnpu/table.rs)

We map sidecar.p4 table names to sidecar-lite equivalents and translate
action parameters where the designs differ for emulation.

All multicast action arms are gated with #[cfg(feature = "multicast")].

## References

- [softnpu #183](oxidecomputer/softnpu#183)
- [propolis #1093](oxidecomputer/propolis#1093)
- [p4rs #240](oxidecomputer/p4#240)
- [sidecar-lite #152](oxidecomputer/sidecar-lite#152)
- tokio: 1.50 (due to softnpu)
- oxide-tokio-rt: 0.1.3 (following-up from tokio's move to 1.50)

Author: zeeshanlakhani

Cargo.lock

@@ -52,9 +52,9 @@ oximeter = { git = "https://github.com/oxidecomputer/omicron", branch = "main" }
 oximeter-producer = { git = "https://github.com/oxidecomputer/omicron", branch = "main" }
 oximeter-instruments = { git = "https://github.com/oxidecomputer/omicron", branch = "main", default-features = false, features = ["kstat"] }
 oxnet = { version = "0.1.4", default-features = false, features = ["schemars", "serde"] }
-propolis = { git = "https://github.com/oxidecomputer/propolis" }
+propolis = { git = "https://github.com/oxidecomputer/propolis", branch = "zl/multicast" }
 smf = { git = "https://github.com/illumos/smf-rs" }
-softnpu-lib = { git = "https://github.com/oxidecomputer/softnpu" , package = "softnpu" , branch = "main"}
+softnpu-lib = { git = "https://github.com/oxidecomputer/softnpu" , package = "softnpu" , branch = "zl/multicast"}
 tofino = { git = "https://github.com/oxidecomputer/tofino", branch = "main" }
 transceiver-controller = { git = "https://github.com/oxidecomputer/transceiver-control", branch = "main" }
 
@@ -82,7 +82,7 @@ libc = "0.2"
 mockall = "0.13.1"
 omicron-zone-package = "0.12"
 openssl = "0.10"
-oxide-tokio-rt = "0.1.2"
+oxide-tokio-rt = "0.1.3"
 parking_lot = "0.12"
 pretty_assertions = "1.4"
 proc-macro2 = "1.0"
@@ -107,7 +107,7 @@ strum = { version = "0.27", features = [ "derive" ] }
 syn = { version = "2.0", features = ["extra-traits"]}
 tabwriter = { version = "1", features = ["ansi_formatting"] }
 thiserror = "1.0"
-tokio = "1.37"
+tokio = "1.50"
 toml = "0.9"
 usdt = "0.6"
 uuid = { version = "1.10", features = [ "v4", "serde" ] }
@@ -117,3 +117,4 @@ internet-checksum = "0.2"
 # It's common during development to use a local copy of various complex
 # dependencies.  If you want to use those, uncomment one of these blocks.
 #
+