A file selection dialog should be opened if "Set reference" button is clicked and an amino acid sequence is selected in the Project View

Scenario:

1. Open "_common_data/fasta/AMINO.fa".
2. Open "_common_data/ugenedb/scerevisiae.bam.ugenedb".
3. Click to the "AMINO263" sequence object in the Project View.
4. Click the "Set reference" button on the toolbar in the Assembly Browser.
   Expected result: a dialog to select a file with a reference is opened.
   Current state: nothing happens.

The behavior should be the same as in case of other unacceptable object is selected in the Project View (for example, an MSA).