🐛 Fix SequenceSet count dups with multiple "*"

[nevans]

In #count, "*" is treated as if it is effectively UINT32_MAX. That was also the intention for #count_with_duplicates (add in #384, not released yet).

Unlike #count, which can assume that * only appears at most once, #count_with_duplicates needs to check each entry.

This means that, e.g:

seqset = SequenceSet["#{UINT32_MAX}:*"]
seqset.count                 => 1
seqset.count_with_duplicates => 1
seqset.count_duplicates      => 0

seqset = SequenceSet["#{UINT32_MAX},*"]
seqset.count                 => 1
seqset.count_with_duplicates => 2
seqset.count_duplicates      => 1