"Coupling Integral 1" test

[int-ptr-ptr]

Description

Please describe the changes/features in this pull request.

• adds test to the first coupling integral in the same vein as the second coupling integral test.

Issue Number

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#1342

Checklist

Please make sure to check developer documentation on specfem docs.

• I ran the code through pre-commit to check style
• THE DOCUMENTATION BUILDS WITHOUT WARNINGS/ERRORS
• I have added labels to the PR (see right hand side of the PR page)
• My code passes all the integration tests
• I have added sufficient unittests to test my changes
• I have added/updated documentation for the changes I am proposing
• I have updated CMakeLists to ensure my code builds
• My code builds across all platforms

[lsawade]

LGTM