Jobs Overhaul: Refactor JobResult.result to JSONField from TextField

[jathanism]

Revisit JobResult.result which is where the Celery task result is stored (different than the JobResult.data field which is used by Jobs for results). Would be best to attempt to marry the two.

This field is currently unused for Jobs, but we should coerce it to a JSONField and set a contract that anything returned from a Job task MUST be JSON. In DCR core it is expected to be encoded/decoded using content_type and content_encoding which we have # eliminated for our implmentation.

Identify a pattern for how the "result" of a Job's Celery task can be returned so that it can be stored on JobResult.result and therefore also handed off to other subtasks for more advanced workflows. See: run_job() return value in PR #3164.

To implement this we could just rename the data field on JobResult to result instead of adding a new field and doing data migration:

https://github.com/nautobot/nautobot/blob/next/nautobot/extras/migrations/0066_jobresult__add_celery_fields.py#LL51-L55C11

Care should be taken to assure that the result serialization will need to be handled to know that it is not being dumped into a TextFied.

[jathanism]

IMO we should also remove the JobResult.data field while we're doing this, since that field is no longer used. In practice, instead of adding JobResult.result and changing it from text to JSON field, it would be cleaner to just rename data to result.

[jathanism]

After further discussion we agreed the correct path is to just add a schema migration to rename the data field to result instead of deleting data and changing the field type of result.

[bryanculver]

Closed with #4133