ci: Add scripts to install ast-grep in Linux jobs

Issue: #28119

.gitlab/.gitignore

@@ -1,6 +1,7 @@
 # Ignore files known to be downloaded by CI jobs.
 /6.9.3-0-202509261208*
 /6.9.3-0-202509261207*
+/ast-grep
 /appimagetool
 /bcc*
 /cmake*

.gitlab/ci/ast-grep-env.sh

@@ -0,0 +1,3 @@
+.gitlab/ci/ast-grep.sh
+export PATH=$PWD/.gitlab/ast-grep:$PATH
+ast-grep --version

.gitlab/ci/ast-grep.sh

@@ -0,0 +1,31 @@
+#!/bin/sh
+
+set -e
+
+readonly version="0.45.3"
+baseurl="https://github.com/ast-grep/ast-grep/releases/download/$version"
+
+case "$(uname -s)-$(uname -m)" in
+    Linux-x86_64)
+        shatool="sha256sum"
+        sha256sum="f8ac830881339d1edee6b2652f54798c0f4da5a827f2db38a08ee31117783ce8"
+        filename="app-x86_64-unknown-linux-gnu"
+        ;;
+    *)
+        echo "Unrecognized platform $(uname -s)-$(uname -m)"
+        exit 1
+        ;;
+esac
+readonly shatool
+readonly sha256sum
+
+readonly tarball="$filename.zip"
+
+cd .gitlab
+
+echo "$sha256sum  $tarball" > ast-grep.sha256sum
+curl -OL "$baseurl/$tarball"
+$shatool --check ast-grep.sha256sum
+mkdir -p ast-grep
+unzip -d ast-grep "$tarball" -x sg
+rm "$tarball" ast-grep.sha256sum