refactor: Split Context into SchemaManger and ActionQueue

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>
tests: Fixed tests broken by refactoring.

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>
tests: Started implementing unit tests for async

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>