Give task owners the ability to choose default setting for getting random contexts

[maxbartolo]

The current default method for getRandomContext() is min, however, there is no way for task owners to change this currently.

Ideally this should be controlled from the task config (e.g. https://dynabench.org/task-owner-interface/qa#advanced) similar to aggregation_metric.

We would need to modify: https://github.com/facebookresearch/dynabench/blob/main/frontends/web/src/common/Annotation/CreateInterface.js#L95.

I suspect the steps required to implement are:

1. Move the taskConfig loading slightly earlier
2. Process the new taskConfig.ATTRIBUTE_NAME attribute accordingly with a default value of min (not sure if we need to make any other changes to make it editable)
3. Change .getRandomContext(this.state.task.id, this.state.task.cur_round) to .getRandomContext(this.state.task.id, this.state.task.cur_round, [], taskConfig.ATTRIBUTE_NAME)

[TristanThrush]

Might be easier to control it with a new place in the task owner settings (similar to how the validation threshold is selected). Do you have any objections to doing that instead?

[maxbartolo]

No, none at all. That works great too!