Detect input format using VEP code

[nuno-agostinho]

1. Update regex for input data detection based on VEP.
2. Create new exported function for input format detection to be used by VEP, avoiding code redundancy.
3. Accept CAID and Region input in web VEP.

Ignore alternative allele when checking VCF format

The idea of this function is to check if this format is VCF: only these columns are needed to check that.

Basically, we should not check for the alternative allele here because:

• The valid characters for the alternative allele are constantly changing with new versions of the VCF specification
• It only checks the first line (other lines may have issues and are ignored)
• The regex may not be up-to-date (it already happened that we support a specific type of alternative allele but forgot to update the regex here)
• If the alternative allele is not supported, it should be the function create_VariationFeatures() from Parse::VCF to return that issue with a warning (and not an error like detect_format(), because the format is still VCF).
• We get user-reported issues related with the strict regex here, even though the line is fully supported by VEP

Related PRs

• Fix web VEP input format detection ensembl-vep#1477
• Update web VEP input detection in JavaScript (e111) public-plugins#717

[nakib103]

Thanks Nuno, looks alright to merge!