[CI/Build] Move pre-commit only scripts to tools/pre_commit (#27657)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tools/pre_commit/png-lint.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# Ensure that *.excalidraw.png files have the excalidraw metadata
+# embedded in them. This ensures they can be loaded back into
+# the tool and edited in the future.
+
+find . -iname '*.excalidraw.png' | while read -r file; do
+	if git check-ignore -q "$file"; then
+		continue
+	fi
+	if ! grep -q "excalidraw+json" "$file"; then
+		echo "$file was not exported from excalidraw with 'Embed Scene' enabled."
+		exit 1
+	fi
+done