ENH: Update NCBITaxonomyDirFmt to accomodate data-version file

[Sann5]

• An fetch-ncbi-taxonomy-data action is planned (ENH: Fetch NCBI Taxonomy Data (input to build_custom_diamond_db action) q2-moshpit#107)
• This will download data from two different sources. Consequently, there is a need to add version information to the resulting artifact.
• This information will be written to an additional file within the artifact, provisionally version.tsv.
• Consequently, there is a need to modify the code in NCBITaxonomyDirFmt to accommodate this extra file.
• Validation for the extra file should also be implemented.
• Test suit should be adjusted/expanded accordingly.

[misialq]

Hey @Sann5, do we still need this or can it be closed?

[Sann5]

@misialq pps I closed the PR but not the issue. Sorry. I close it now.