Add support for subfield t,g,k (245 field)

[kirkhess]

If subfield $t and subfield $g are included in the title (which is unlikely but possible), the subfields will no longer be in the order they originally were and $g and $t will not be assigned to their associated strings. However, the same is true for $k which is used much more often.

Example:
730 02 $a High on the hill $t Why is there a $t? $n Part 2 $p The good part $d 1956 $f 1955 $g misc info $k Papers $l English $m Piano $o arranged $r C major $s Version B $0 http://id.loc.gov/authorities/names/no2010189088 $1 https://id.oclc.org/worldcat/entity/E39PCGmgQGB866cRJQCtrRqvpP $1 https://id.loc.gov/resources/works/5711546

Convert with marc2bibframe2, back to MARC w/ bibframe2marc (roundtrip):

Post-processing fix:

Field ends up with the t, g, k appended to subfield a