Misc fixes for webinar demo

[annehaley]

This PR fixes some miscellaneous behavior that I discovered when preparing my demo for the webinar:

• The legend panel should only show that feature color props are being applied if those color props are present on some features.
• View states were not being fetched properly due to a bug in the GuardianFilter in access_control.py
• Fixed project selection behavior in project configuration page (it would reselect the previous project after creating a new project)
• Added a trailing slash to the API function for deleting a dataset
• Imported non-analytics tasks to ensure that they are registered by celery

[cloudflare-workers-and-pages]

Deploying geodatalytics with    Cloudflare Pages

Latest commit:	03671f5
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View logs

[BryonLewis]

a few questions, I don't think any are blockers and could be implemented/updated if required.

[brianhelba]

1 question, 1 small code simplification

[brianhelba]

I think we eventually need to be importing all of the tasks to register them, but that might be outside the scope of this PR.

[brianhelba]

I haven't reviewed the Vue code, but the Python side makes sense.

[brianhelba]

You can add:

__all__ = [
    'convert_chart',
    'convert_dataset',
]

to make it happy about unused imports.

[brianhelba]

You might be able to just do:

import .chart
import .dataset

instead.

[BryonLewis]

I think the changes made to the getColorPropsCoverage make it clearer what is happening, thanks.