mctp-estack: Add StepExecutor for testing

This is a specialised executor to run async futures with more control.
Can be used to partially run a future such as recv(), then adjust
the clock before proceeding, when testing timeouts.

Signed-off-by: Matt Johnston <[email protected]>

Author: mkj

Cargo.lock

@@ -23,9 +23,11 @@ uuid = { workspace = true }
 critical-section = { version = "1.2.0", features = ["std"] }
 embedded-io-adapters = { workspace = true }
 env_logger =  { workspace = true }
+futures = "0.3"
 proptest = { workspace = true }
 smol = { workspace = true }
 
+
 [features]
 default = ["log"]
 std = ["mctp/std"]