Add a mock server for tests [develop]

[Samweli]

Based on https://github.com/ConservationInternational/trends.earth/pull/742,

Adds the following changes that are related to the tests.

• Updates on the api module now using a APIClient class to store and interface all the API related functionality this makes the module testable.
• Removal of unused methods in calculate.py
• Added a new mock API server for running tests local and on CI
• Include initial test for the calculate_ldn alg.

[azvoleff]

@Samweli I get an immediate crash on trying to refresh the dataset list if I try to run this branch in QGIS, so I'm hesitant to merge at this point as I it would complicate testing any other PRs relative to develop.

I don't get a crash report when it crashes, but I do see this in the log pane before QGIS closes (looks like a missing method):

Are you able to run this on your machine?

[Samweli]

I don't get a crash report when it crashes, but I do see this in the log pane before QGIS closes (looks like a missing method):

@azvoleff same thing happened to me, I have made a fix for it here https://github.com/ConservationInternational/trends.earth/pull/745/commits/60f5ae6ce64e53bc3ce04da860d56e74b47c095a

[azvoleff]

Still hesitant to merge this one @Samweli. It seems to break task submission - when you try to submit a remote task it appears nothing happens (the job doesn't show up on our server nor in the plugin, and there are no error messages shown to the user). It seems to be an issue with getting the token. Also see above comments (particularly on removing the json_geom_to_geojson function as that will break several local algorithms).

[Samweli]

when you try to submit a remote task it appears nothing happens

@azvoleff this was indeed an issues in getting the token, I have fixed and tested it see the below screenshot

[azvoleff]

Thanks - looks good!