Import and modernize bocoup/test262-regexp-generator #1676

	name: 'esmeta test262'

	on: [pull_request]

	jobs:
	esmeta-test262:
	name: 'esmeta test262'
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v4
	- name: Setup JDK
	uses: actions/setup-java@v3
	with:
	distribution: temurin
	java-version: 17
	- name: Setup SBT
	uses: sbt/setup-sbt@v1
	if: ${{ hashFiles('/usr/bin/sbt') == '' }}
	# https://www.peterbe.com/plog/how-to-run-workflow-step-if-a-file-exists
	- name: Add to PATH
	shell: bash
	run: \|
	echo "ESMETA_HOME=$(pwd)/vendor/esmeta" >> $GITHUB_ENV
	- name: download esmeta
	run: \|
	mkdir -p "${ESMETA_HOME}"
	git clone --branch v0.4.2 --depth 1 https://github.com/es-meta/esmeta.git "${ESMETA_HOME}"
	cd "${ESMETA_HOME}" && git submodule update --init --depth 1
	- name: build esmeta
	working-directory: ${{ env.ESMETA_HOME }}
	run: sbt assembly
	- name: run test262
	run: \|
	git fetch origin main
	paths=$(git diff --diff-filter ACMR --name-only origin/main.. -- test/)
	if [ "$paths" == "" ]; then
	echo No test files added or modified. Exiting.
	exit 0
	fi
	echo New or modified test files:
	echo "$paths"
	"${ESMETA_HOME}"/bin/esmeta test262-test -status -test262dir=$(pwd) $paths

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