Add AlertLifeCycleObserver that allows consumers to hook into Alert life cycle #255

	---
	name: CI
	on: # yamllint disable-line rule:truthy
	pull_request:
	workflow_call:
	jobs:
	test_frontend:
	name: Test alertmanager frontend
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- run: make clean
	- run: make all
	working-directory: ./ui/app
	- run: make assets
	- run: make apiv2
	- run: git diff --exit-code

	build:
	name: Build Alertmanager for common architectures
	runs-on: ubuntu-latest
	strategy:
	matrix:
	thread: [ 0, 1, 2 ]
	steps:
	- uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
	- uses: prometheus/promci@3cb0c3871f223bd5ce1226995bd52ffb314798b6 # v0.1.0
	- uses: ./.github/promci/actions/build
	with:
	promu_opts: "-p linux/amd64 -p windows/amd64 -p linux/arm64 -p darwin/amd64 -p darwin/arm64 -p linux/386"
	parallelism: 3
	thread: ${{ matrix.thread }}

	test:
	name: Test
	runs-on: ubuntu-latest
	# Whenever the Go version is updated here, .promu.yml
	# should also be updated.
	container:
	image: quay.io/prometheus/golang-builder:1.21-base
	steps:
	- uses: actions/checkout@v3
	- uses: prometheus/[email protected]
	- uses: ./.github/promci/actions/setup_environment
	- run: make
	- run: git diff --exit-code

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