Import primers from SnapGene, Genbank and other files

The main reason why users would import a sequence from a file instead of from a database is that they have already done some work with it, mainly creating annotations and primers. Primers are carried over in .dna and .gb files, and users may want to load them too into the SYC primer table.

I can think of different ways we can do this:

• Add checkbox when importing the sequence source file so all primers are imported (maybe not a very flexible approach).
• Support parsing such file types in the recent "Import primers" function. We can reuse the "validation table" and add checkboxes so the user can decide which primers to import. The drawback is that the user would be uploading the file twice to get first the sequence and then the primers.
• Create a new feature like "import primers from source", where SYC reads the primer information in the already created sources.

Any thoughts @manulera ?

Start by reviewing the existing sequence-source import flow and the recent "Import primers" function mentioned in the issue. Decide which supported formats and import workflow to implement, then verify that primers from .dna and .gb files can be selected or imported into the SYC primer table.