Run dag-processor separate from scheduler in local dev

[BasPH]

Description

In advance of Airflow 3, where the DAG processor will always run as a separate process, I suggest running the DAG processor separately from the scheduler in the local dev setup.

Noteworthy details:

• I didn't add a way to configure this on/off, since the option to run the DAG processor separately was added in Airflow 2.3.0. Since the oldest supported Airflow that Astro supports is Airflow 2.7, I assume the option to separate the DAG processor is available to all users.
• New commands:
  • astro dev logs -d/--dag-processor
  • astro dev bash -d/--dag-processor

Go is a bit out of my comfort zone and I'm unfamiliar with the repository setup, so I'd appreciate a thorough review.

🎟 Issue(s)

Related #XXX

🧪 Functional Testing

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📸 Screenshots

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📋 Checklist

• Rebased from the main (or release if patching) branch (before testing)
• Ran make test before taking out of draft
• Ran make lint before taking out of draft
• Added/updated applicable tests
• Tested against Astro-API (if necessary).
• Tested against Houston-API and Astronomer (if necessary).
• Communicated to/tagged owners of respective clients potentially impacted by these changes.
• Updated any related documentation