revive-runner: add a utility binary for local contract execution (#284)

I had this in mind for a while but never implemented a standalone binary
so far because I always end up writing an integration test anyways.

However, using a standalone version of the pallet based on the
revive-runner crate is something people filing in bug reports do
anyways, for example:
https://github.com/paritytech/revive/issues/266
https://github.com/paritytech/contract-issues/issues/54
---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

Makefile

@@ -5,6 +5,7 @@
 	install-wasm \
 	install-llvm-builder \
 	install-llvm \
+	install-revive-runner \
 	format \
 	clippy \
 	machete \
@@ -39,6 +40,9 @@ install-llvm: install-llvm-builder
 	revive-llvm clone
 	revive-llvm build --llvm-projects lld --llvm-projects clang
 
+install-revive-runner:
+	cargo install --path crates/runner --no-default-features
+
 format:
 	cargo fmt --all --check