mesh_channel: hide RPC response receiver from callers #1410

Job	Run time
build and check docs [x64-windows]	9m 18s
build artifacts [x64-linux]	5m 56s
build mdbook guide	1m 23s
build openhcl [aarch64-linux]	5m 26s
build openhcl [x64-linux]	7m 52s
clippy [windows], unit tests [x64-windows]	11m 23s
clippy [linux, macos], unit tests [x64-linux]	8m 16s
clippy [linux-musl, misc nostd], unit tests [x64-linux-musl]	7m 25s
unit tests [aarch64-windows]	6m 56s
build and check docs [x64-linux]	2m 56s
test flowey local backend	3m 13s
xtask fmt (linux)	2m 34s
build artifacts (not for VMM tests) [aarch64-windows]	4m 39s
build artifacts (for VMM tests) [aarch64-windows]	10m 22s
build artifacts (not for VMM tests) [x64-windows]	4m 46s
build artifacts (for VMM tests) [x64-windows]	10m 23s
build artifacts [aarch64-linux]	5m 29s
xtask fmt (windows)	7m 6s
run vmm-tests [aarch64-windows]	5m 46s
run vmm-tests [x64-linux]	3m 37s
run vmm-tests [x64-windows-amd]	11m 45s
run vmm-tests [x64-windows-intel]	9m 34s
openvmm checkin gates	6s
	2h 26m 11s

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