Do not require selecting a license when creating a new dataset

[kabilar]

Description

1. Datasets on lincbrain.org are private to the LINC team and collaborators, and thus are not currently meant for public dissemination. Furthermore, several datasets are uploaded for testing purposes.
2. Currently, users must select a Creative Commons license (CC-BY-4.0, CC0-1.0) for open data sharing when creating a new dataset.

Proposed suggestion

1. Remove the requirement for selecting a license.
   1. When creating a New Dataset on the front-end, replace the License field with the NIH Award Number field by removing the if-clause from this if-else statement.
   2. The resulting behavior would mirror creating an embargoed Dandiset on dandiarchive.org.
   3. Hopefully this change won't require updates to the dandi-schema repo but may break some logic in the lincbrain-cli which we would need to fix.

cc @aaronkanzer @satra @ayendiki

[satra]

is there a reason not to make every dataset embargoed by default? i would also suggest reviewing the implications in relation to the internal datasharing policy that was signed by all the connects PIs.

also is this really an issue within linc? i would prioritize other efforts over an edge case of the internal portal.