Nextcloud/Owncloud input data source accepts invalid file types

[pansapiens]

For genomics pipelines, restrict the filetypes that can be 'added to cart' by file extension, in the UI.
Otherwise it is possible to add a Nextcloud 'directory' that ends up as an empty file.
Restricting to to .gz, .fastq, .fq, .fa, .fna, .fasta, .gtf, .gff, .tar should cover all required input file types and prevent oddball input files being added.
Possibly apply this to other input file sources (files on web, files on web via samplesheet).
Potentially filter so these never appear in the list of selectable files (or include them but unselectable, strikethough/greyed out).