tr: check a complemented SET1 the way GNU does

[Socialpranker]

With -c, uutils checks SET2's [:upper:]/[:lower:] against positions in SET1, but a complemented SET1 has no such positions. It also reports the complement rule before the "longer than SET2" rule. Found by diffing against GNU 9.12:

$ echo AbC1z | tr -c '[:upper:]' '[:lower:]'
tr: when translating with string1 longer than string2,     # GNU
the latter string must not end with a character class
tr: when translating with complemented character classes,  # uutils
string2 must map all characters in the domain to one

$ echo AbC1z | tr -c '\000-\377' '[:upper:]'
AbC1z                                                      # GNU
tr: when translating, every 'upper'/'lower' in set2 must   # uutils
be matched by a 'upper'/'lower' in the same position in set1

The fix skips the alignment check under -c and runs the complement check after the length check. Tests added in test_tr.rs.

[xtqqczze]

Code Quality / Style/lint (windows-latest, feat_os_windows) (pull_request) failures tracked by #14916.

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/id/setgid is no longer failing!