Refactor imports around utils and logic

Is your feature request related to a problem? Please describe.
During development I encountered a particularly long import chain that ended in a circular ImportError:

File "/home/joe/git/janeway/src/cms/models.py", line 15, in <module>
    from core.model_utils import AbstractBleachModelMixin
  File "/home/joe/git/janeway/src/core/model_utils.py", line 49, in <module>
    from utils import logic
  File "/home/joe/git/janeway/src/utils/logic.py", line 11, in <module>
    from core.middleware import GlobalRequestMiddleware
  File "/home/joe/git/janeway/src/core/middleware.py", line 19, in <module>
    from press import models as press_models
  File "/home/joe/git/janeway/src/press/models.py", line 15, in <module>
    from core import models as core_models
  File "/home/joe/git/janeway/src/core/models.py", line 36, in <module>
    from core import files, validators
  File "/home/joe/git/janeway/src/core/files.py", line 32, in <module>
    from utils import models as util_models
  File "/home/joe/git/janeway/src/utils/models.py", line 20, in <module>
    from utils.importers.up import get_input_value_by_name
  File "/home/joe/git/janeway/src/utils/importers/up.py", line 17, in <module>
    from utils.importers import shared
  File "/home/joe/git/janeway/src/utils/importers/shared.py", line 17, in <module>
    from journal import models as journal_models
  File "/home/joe/git/janeway/src/journal/models.py", line 26, in <module>
    from core import (
  File "/home/joe/git/janeway/src/core/workflow.py", line 12, in <module>
    from review.logic import assign_editor
  File "/home/joe/git/janeway/src/review/logic.py", line 32, in <module>
    from events import logic as event_logic
  File "/home/joe/git/janeway/src/events/logic.py", line 7, in <module>
    from submission import models as submission_models
  File "/home/joe/git/janeway/src/submission/models.py", line 37, in <module>
    from core.model_utils import(
ImportError: cannot import name 'AbstractLastModifiedModel' from partially initialized module 'core.model_utils' (most likely due to a circular import) (/home/joe/git/janeway/src/core/model_utils.py)

Describe the solution you'd like
We need to refactor the imports on this chain a bit to make it less likely that we will encounter this error when using model_utils or logic inside models files.

Additional context
This was fixed temporarily by moving an import into a method here:

diff --git a/src/core/model_utils.py b/src/core/model_utils.py
index 2f94757d..89753653 100644
--- a/src/core/model_utils.py
+++ b/src/core/model_utils.py
@@ -46,7 +46,6 @@ from modeltranslation.utils import auto_populate
 from PIL import Image
 import xml.etree.cElementTree as et
 
-from utils import logic
 from utils.logger import get_logger
 
 logger = get_logger(__name__)
@@ -96,6 +95,8 @@ class AbstractSiteModel(models.Model):
         return obj
 
     def site_url(self, path=None):
+        # This import is here to avoid circular imports
+        from utils import logic
         return logic.build_url(
             netloc=self.domain,
             scheme=self._get_scheme(),

Start by tracing the import chain through src/core/model_utils.py, src/utils/logic.py, src/core/middleware.py, src/press/models.py, src/core/models.py, src/core/files.py, src/utils/models.py, src/utils/importers/up.py, src/utils/importers/shared.py, src/journal/models.py, src/core/workflow.py, src/review/logic.py, src/events/logic.py, and src/submission/models.py. Compare it with the temporary method-local import in AbstractSiteModel.site_url; done means the circular ImportError no longer occurs when model_utils or logic is used from model files.