Break lal dependency cycle

There were a number of places where lal was imported at module
scope, making a dependency cycle.
3 jobs for lal-optional-imports in 2 minutes and 13 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
passed #945597
build-python27

00:01:41

passed #945598
build-python37

00:01:12

 
  Docs
passed #945599
docs

00:00:31