Replace all previously text-based json fields with JSONBlob

This JSONBlob field type is a wrapper around Django's new generic
JSONField, but with the database column type forced to be text.  This
should behave close enough to our old wrapper around
django-jsonfield's JSONField and will avoid needing to do the
out-of-band database migration.

awx/main/models/mixins.py

@@ -24,7 +24,7 @@ from awx.main.utils import parse_yaml_or_json, get_custom_venv_choices, get_lice
 from awx.main.utils.execution_environments import get_default_execution_environment
 from awx.main.utils.encryption import decrypt_value, get_encryption_key, is_encrypted
 from awx.main.utils.polymorphic import build_polymorphic_ctypes_map
-from awx.main.fields import AskForField
+from awx.main.fields import AskForField, JSONBlob
 from awx.main.constants import ACTIVE_STATES
 
 
@@ -103,7 +103,7 @@ class SurveyJobTemplateMixin(models.Model):
     survey_enabled = models.BooleanField(
         default=False,
     )
-    survey_spec = prevent_search(models.JSONField(default=dict, blank=True))
+    survey_spec = prevent_search(JSONBlob(default=dict, blank=True))
     ask_variables_on_launch = AskForField(blank=True, default=False, allows_field='extra_vars')
 
     def survey_password_variables(self):
@@ -365,10 +365,9 @@ class SurveyJobMixin(models.Model):
         abstract = True
 
     survey_passwords = prevent_search(
-        models.JSONField(
+        JSONBlob(
             default=dict,
             editable=False,
-            null=True,
             blank=True,
         )
     )