fix(gsa): prevent exception on gsamemb2d from gwa (SPEC-522)

[dtnaughton]

Description & motivation

Member topology that has empty brackets throws an exception e.g.

Changes:

• Remove empty list entries after splitting GWA topology

To-do before merge:

N/A

Screenshots:

Validation of changes:

• Added unit test for specific case
• Manual test sending data to Speckle

Checklist:

• My pull request follows the guidelines in the Contributing guide?
• My pull request does not duplicate any other open Pull Requests for the same update/change?
• My commits are related to the pull request and do not amend unrelated code or documentation.
• My code follows a similar style to existing code.
• I have added appropriate tests.
• I have updated or added relevant documentation.

References