[CI/Build] Add shell script linting using shellcheck (#7925)

Signed-off-by: Russell Bryant <rbryant@redhat.com>

tools/shellcheck.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+scversion="stable"
+
+if [ -d "shellcheck-${scversion}" ]; then
+    export PATH="$PATH:$(pwd)/shellcheck-${scversion}"
+fi
+
+if ! [ -x "$(command -v shellcheck)" ]; then
+    if [ "$(uname -s)" != "Linux" ] || [ "$(uname -m)" != "x86_64" ]; then
+        echo "Please install shellcheck: https://github.com/koalaman/shellcheck?tab=readme-ov-file#installing"
+        exit 1
+    fi
+
+    # automatic local install if linux x86_64
+    wget -qO- "https://github.com/koalaman/shellcheck/releases/download/${scversion?}/shellcheck-${scversion?}.linux.x86_64.tar.xz" | tar -xJv
+    export PATH="$PATH:$(pwd)/shellcheck-${scversion}"
+fi
+
+# TODO - fix warnings in .buildkite/run-amd-test.sh
+find . -name "*.sh" -not -path "./.deps/*" -not -path "./.buildkite/run-amd-test.sh" -exec shellcheck {} +