Fix tab display with missing protein domain information

If there are no protein domains detected in a gene product, the "Protein Data" section of the gene page is not displayed at all. However, there are information in there which also make sense without domains, e.g. mass, charge, isoelectric point, etc. as well as transmembrane regions.
This PR adds support for showing only the tabs in the protein data section which actually are backed by data retrieved from Crawl, automatically hiding tabs with no such data.