docker: Add rust-sdk memcheck target.

docker: Separate and tweak cargo cache paths.

ci: Improve memcheck job targets.

cargo: Add missing debug syms to bench profile.

docker: Optimize layer copying.

Signed-off-by: Jason Volk <jason@zemos.net>

docker/Dockerfile.nix

@@ -4,6 +4,7 @@ FROM input AS nix-base
 
 WORKDIR /
 COPY --link --from=input . .
+
 RUN \
 --mount=type=cache,dst=/nix,sharing=shared \
 --mount=type=cache,dst=/root/.cache/nix,sharing=shared \