feat(workflow): make common linter re-usable #260

	---
	# This action is centrally managed in https://github.com/<organization>/.github/
	# Don't make changes to this file in this repo as they will be overwritten with changes made to the same file in
	# the above-mentioned repo.

	# Validate Renovate config files.

	name: renovate config validator

	on:
	pull_request:
	branches: [master]
	types: [opened, synchronize, reopened]

	concurrency:
	group: "${{ github.workflow }}-${{ github.ref }}"
	cancel-in-progress: true

	jobs:
	renovate-config-validator:
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v4

	- name: Find additional files
	id: find-files
	run: \|
	files=$(find . -type f -iname "renovate.json")

	echo "found files: $files"

	# do not quote to keep this as a single line
	echo found=${files} >> $GITHUB_OUTPUT

	- name: Install npm dependencies
	if: ${{ steps.find-files.outputs.found != '' }}
	run: npm install --global renovate

	- name: renovate config validator
	if: ${{ steps.find-files.outputs.found != '' }}
	run: \|
	# disable error exit code
	set +e
	status=0

	for FILE in ${{ steps.find-files.outputs.found }}; do
	file_status=0
	renovate-config-validator --strict $FILE \|\| file_status=$?

	# set github step summary
	if [ $file_status -ne 0 ]; then
	echo ":x: $FILE: failed" >> $GITHUB_STEP_SUMMARY
	status=1
	else
	echo ":white_check_mark: $FILE: passed" >> $GITHUB_STEP_SUMMARY
	fi
	done

	# exit with error if any file failed
	exit $status

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