Content Browser columns should not be determined by a randomly picked asset

SAssetView::SetMajorityAssetType for most asset types randomly picks a visible asset to grab the metadata from, which is what derives the CB columns. This can become a problem if the random asset it picks isn't loaded, hasn't been re-saved recently or is missing some metadata that is present on other assets. Which leads to very inconsistent behavior on which columns show up in the CB.

Potential solutions:

• Use the CDO of the type to determine the columns instead of picking an asset
• Always do a union of all assets present to pick the columns (this happens for some asset types via AssetClassesRequiringDynamicTags