(core) cicd pipelines should allow notifications

[malachi-constant]

Is your idea related to a problem? Please describe.
Users would like to know when DDK CI/CD pipelines are failing.

Describe the solution you'd like
The DDK CI/CD Pipelines should handle alerting (CloudWatch/SNS) via a dedicated method. For example:

     CICDPipelineStack(
            cdk_app,
            id="dummy-pipeline",
            environment_id="dev",
            pipeline_name="dummy-pipeline",
        )
        .add_source_action(repository_name="dummy-repository")
        .add_synth_action()
        .build()
        .add_security_lint_stage()
        .add_test_stage()
        .add_stage("dev", DevStage(cdk_app, "dev"))
        .synth()
        .add_notifications()

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