Add fallback to merge samples without stacking in amdirt viewer

[alexhbnr]

This PR addresses the issue on AncientMetagenomeDir. In brief, if a sample has more than one sample accession number (SRS or ERS code) in the sample table, we typically split this list of comma-separated sample accession numbers before searching for them in the library table.

However, there are a few samples for which all sequencing data in the library table has been tagged with the same comma-separated list of sample accession numbers. For these, splitting the comma-separated numbers destroys the link to the data in the library table.

To consider the latter case, I implemented a fallback option that when after splitting the comma-separated list no library information has been found, then it is tested whether not-splitting the sample accession numbers will yield library information.

[jfy133]

During testing I hit the following error:

Select ancientsinglegneome-hostassociated table

1. Select all Neukamm2020 samples, and validate samples
2. Select all Neukam2020 libraries (note: this DOES show all associated libraries), validate libraries
3. I get the following error after pressing validate libraries, and the bibtext button doesn't load

All working buttons downloaded stuff as expected however!