Better error message for input MSA

[lczech]

Given a FASTA file with unaligned sequences, when calling with --msa file.fasta, without specifying --msa-format FASTA, the error message is

ERROR: Error loading MSA: cannot parse any format supported by RAxML-NG!
Please re-run with --msa-format <FORMAT> and/or --log debug to get more information.

While of course unaligned sequences are not supported, the error message could be better here. Ideally, it should be the same as when actually specifying --msa-format FASTA, which reports

ERROR: Error loading MSA: FASTA file does not contain equal size sequences

for the same unaligned data.