Enhance reporting, add shellcheck (#28240) #1

	name: Migration-assist Sync
	on:
	push:
	branches:
	- master
	paths:
	- "server/channels/db/**"

	jobs:
	check:
	name: Check if migration-assist have been synced
	runs-on: ubuntu-22.04
	defaults:
	run:
	working-directory: server
	steps:
	- name: Checkout mattermost project
	uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
	- name: Checkout migration-assist project
	uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
	with:
	repository: mattermost/migration-assist
	ref: main
	path: migration-assist
	- name: Compare migration-assist with mattermost
	run: \|
	diff --brief --recursive channels/db/migrations/postgres /home/runner/work/mattermost/mattermost/migration-assist/queries/migrations/postgres
	- name: Report migrations are not in sync via webhook
	if: ${{ failure() }}
	uses: mattermost/action-mattermost-notify@b7d118e440bf2749cd18a4a8c88e7092e696257a # v2.0.0
	with:
	MATTERMOST_WEBHOOK_URL: ${{ secrets.MM_COMMUNITY_MIGRATIONS_INCOMING_WEBHOOK_FROM_GH_ACTIONS }}
	TEXT: \|-
	#### ⚠️ Migration-assist embedded migrations are not in sync ⚠️
	* Job: [github.com/mattermost/mattermost:${{ inputs.name }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})
	* Whenever a new migration has been added to the schema migrations, we should also update the embedded migrations in the `migration-assist` repository to keep them in sync. Please include newer migrations and cut a release for `migration-assist` to include them in the next release.
	* cc @ibrahim.acikgoz

Provide feedback