RNPxl: Empty PSMs and Proteins table

[hannesveit]

These tables are always created by PD and are currently empty. According to Thermo, it is impossible to remove them.

We could, however, think about filling them with the PSMs / proteins found by the regular search engine run (without cross links) that is currently just used internally for filtering purposes. This way, we would avoid useless empty result tables and provide some additional information which might be valuable.

However, empty tables do have the advantage that the user does not confuse them with the actual results and is more likely to find the "RNPxls" table.