cargo: Add codesigning runner script for MacOS

On MacOS, communicating with the hypervisor requires that a binary be
signed with an "entitlement" `com.apple.security.hypervisor`. This
commit adds a script that locally signs and then runs a binary, and
configures Cargo to use that script to run tests/exmaples/etc.

Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

Author: syntactically

.cargo/config.toml

@@ -0,0 +1,2 @@
+[target.'cfg(target_os = "macos")']
+runner = "dev/macos-sign-and-run.sh"

dev/macos-entitlements.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.security.hypervisor</key>
+	<true/>
+</dict>
+</plist>

dev/macos-sign-and-run.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+
+codesign -f -s - --entitlements "$(dirname "$0")/macos-entitlements.plist" "$1"
+exec "$@"