build/bot: add mac build script (#24917)

build/bot/macos-build.sh

+#!/bin/bash
+
+set -e -x
+
+# -- Build for macOS and upload to Azure
+go run build/ci.go install -dlgo
+go run build/ci.go archive -type tar # -signer OSX_SIGNING_KEY -upload gethstore/builds
+
+# # -- CocoaPods
+# gem uninstall cocoapods -a -x
+# gem install cocoapods
+# mv ~/.cocoapods/repos/master ~/.cocoapods/repos/master.bak
+# sed -i '.bak' 's/repo.join/!repo.join/g' $(dirname `gem which cocoapods`)/cocoapods/sources_manager.rb
+# git clone --depth=1 https://github.com/CocoaPods/Specs.git ~/.cocoapods/repos/master
+# pod setup --verbose
+
+# -- Check XCode version
+xctool -version
+xcrun simctl list
+
+# # -- Build for iOS and upload to Azure
+# go run build/ci.go xcode -signer IOS_SIGNING_KEY -upload gethstore/builds