Meta+Toolchain+CI: Add a script to bootstrap vcpkg

And hook it into ladybird.sh for convenience. The script will set up
PATH and other environment variables automatically.

On CI, vcpkg is theoretically already installed on Linux machines, but
not with the right environment variables, and not on macOS. So this also
makes CI use this script to bootstrap vcpkg.

Toolchain/BuildVcpkg.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+# This script builds the vcpkg dependency management system
+set -e
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+# shellcheck source=/dev/null
+. "${DIR}/../Meta/shell_include.sh"
+
+exit_if_running_as_root "Do not run BuildVcpkg.sh as root, parts of your Toolchain directory will become root-owned"
+
+GIT_REPO="https://github.com/microsoft/vcpkg.git"
+GIT_REV="01f602195983451bc83e72f4214af2cbc495aa94" # 2024.05.24
+PREFIX_DIR="$DIR/Local/vcpkg"
+
+mkdir -p "$DIR/Tarballs"
+pushd "$DIR/Tarballs"
+    [ ! -d vcpkg ] && git clone $GIT_REPO
+
+    cd vcpkg
+    git fetch origin
+    git checkout $GIT_REV
+
+    ./bootstrap-vcpkg.sh -disableMetrics
+
+    mkdir -p "$PREFIX_DIR/bin"
+    cp vcpkg "$PREFIX_DIR/bin"
+popd