bebop: fix concurrent map writes

[gen2thomas]

Solved issues and/or description of the change

Fix #398 by introducing a dedicated network frame generator object and mutex on generate.

Manual test

none

Checklist

• The PR's target branch is 'hybridgroup:dev'
• New and existing unit tests pass locally with my changes (e.g. by run make test_race)
• No linter errors exist locally (e.g. by run make fmt_check)
• I have performed a self-review of my own code