add script to generate shell spec from runtime wasm

scripts/create_shell_spec.sh

@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+
+usage() {
+    echo Usage:
+    echo "$0 <srtool compressed runtime>"
+    exit 1
+}
+
+set -e
+
+rt_path=$1
+
+binary="./target/release/polkadot-collator"
+
+# build the chain spec we'll manipulate
+$binary build-spec --chain shell > shell-spec-plain.json
+
+# convert runtime to hex
+cat $rt_path | od -A n -v -t x1 |  tr -d ' \n' > shell-hex.txt
+
+# replace the runtime in the spec with the given runtime
+cat shell-spec-plain.json | jq --rawfile code shell-hex.txt '.genesis.runtime.system.code = ("0x" + $code)' > edited-shell-plain.json
+
+# build a raw spec
+$binary build-spec --chain edited-shell-plain.json --raw > shell-spec-raw.json
+
+# build genesis data
+$binary export-genesis-state --parachain-id=1000 --chain shell-spec-raw.json > shell_genesis
+
+# build genesis wasm
+$binary export-genesis-wasm --chain shell-spec-raw.json > shell_wasm