v2.34.0 — a blank V or J call is proposed from the junction

A submission is allowed to leave one side out, and a blank is not a reason to refuse the record.
The locus comes from the side that is named, so the proposal is always within the right locus, and
the junction is the evidence about the missing one.

Over VDJdb's 192,726 distinct curation keys, 3,130 leave a side blank (644 with no V, 2,947 with no
J). 2,532 of those now get a segment and 2,504 come back good with both boundaries placed. The 598
that stay refused name neither side, so there is no locus to propose within.

Cdr3Markup.proposed (and the proposed column) says which side was never curated — a different
fact from the allele flag, which means the submission named a different allele of the same gene.

An unresolvable call is still refused: TRBVnope*01 keeps its FailedBadSegment. A submission
that names something wrong has a defect a curator must see; one that names nothing has a gap the
junction can fill.

This closes the last reason a consumer had to carry its own segment proposer alongside cdr3fix.

Full changelog: https://github.com/antigenomics/arda/blob/master/CHANGELOG.md