refactor: change launch files to support new nebula architecture

[mojomex]

PR Type

• Improvement

Related Links

• TIER IV internal link -- parent issue
• TIER IV internal link -- this issue

Description

This PR makes the changes necessary to support the new Nebula single-node architecture.
These changes can be summarized as:

• merge the separate Nebula nodes into one in the launch file
• find and read default sensor config file in case none is specified. Parameters specified as arguments will override the values in the file

⚠️ This PR has to be merged in a coordinated manner with the corresponding PRs listed below. The timeline is currently being discussed.

Review Procedure

Compile and run Edge.Auto on a sample rosbag and see if pointclouds are output.

Pre-Review Checklist for the PR Author

PR Author should check the checkboxes below when creating the PR.

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Checklist for the PR Reviewer

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• Commits are properly organized and messages are according to the guideline
• (Optional) Unit tests have been written for new behavior
• PR title describes the changes

Post-Review Checklist for the PR Author

PR Author should check the checkboxes below before merging.

• All open points are addressed and tracked via issues or tickets

CI Checks

• Build and test for PR: Required to pass before the merge.