Omit license and dup fields from netkans, handle GH source ZIPs

[HebaruSan]

Motivation

• As of Allow licenses to be absent from netkans CKAN#4137, license is now optional in netkans and is populated from the host APIs
• Since multi-hosted mods are processed independently and then merged together, it's not necessary to duplicate all fields
• When the SpaceDock Adder checks a GitHub repo for a download ZIP, it only examines assets attached to a release, even though the Inflator is capable of handling releases without assets by checking the source ZIP

Changes

• Now the SpaceDock Adder doesn't populate license
• Now tags, depends, and install are only populated in one of the sections for multi-hosted mods
• Now if a GitHub repo has a release but no assets, x_netkan_github.use_source_archive: true is set and the source archive is passed to the Mod Analyzer

[HebaruSan]

The spurious SpaceWarpInfo warnings were fixed in KSP-CKAN/CKAN#4171, so this is now sensible to merge.