sstablesplit incorrectly ignores SStable files

When trying to test sstablesplit on a valid sstable I see messages like

"Skipping non sstable file mc-7-big-Data.db"

This is clearly an sstable, so it looks like the parser for valid sstables is still assuming the old file name format.

StandaloneSplitter appears to call tryComponentFromFilename which calls fromFilename in src/java/org/apache/cassandra/io/sstable/Component.java

Checking the in Component.java I see a comment that looks like the code is looking for the old sstable file name format:

• {@code * Filename of the form "<ksname>/<cfname>-[tmp-][<version>-]<gen>-<component>", * }