Add Delta Lake to Iceberg Yaml blueprint IT

[derrickaw]

1. Add Delta Lake to Iceberg Yaml blueprint IT
2. Add a new blueprints folder for post commit tests for blueprints. Currently, we have individual transforms tested in precommit and postcommit, but the blueprints we do have are currently mocked examples.
3. Passing run - https://github.com/apache/beam/actions/runs/30488274371

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