throw more informative error when fail to parse sstable generation

since scylla 5.4, the sstables are named with a uuid-based identifier
instead of integer-based one. so the java tools inherited from cassandra
3.x branch do not support it, and throw an
`UnsupportedOperationException` when parsing a sstable name with the
integer-based generation. like:

```console
$ sstablemetadata me-3gbp_1glu_4e6g020ns4px173el0-big-Data.db
Exception in thread "main" java.lang.NumberFormatException: For input string: "3gbp_1glu_4e6g020ns4px173el0"
        at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.base/java.lang.Integer.parseInt(Integer.java:652)
        at java.base/java.lang.Integer.parseInt(Integer.java:770)
        at org.apache.cassandra.io.sstable.Descriptor.fromFilename(Descriptor.java:280)
        at org.apache.cassandra.io.sstable.Descriptor.fromFilename(Descriptor.java:228)
        at org.apache.cassandra.io.sstable.Descriptor.fromFilename(Descriptor.java:217)
        at org.apache.cassandra.tools.SSTableMetadataViewer.main(SSTableMetadataViewer.java:150)
```

the user experience is poor when seeing this exception. so let's throw
a better exception, so the new output looks like:

```console
$ sstablemetadata me-3gbr_0y9h_03n682utcozh4xc6c7-big-Data.db
Exception in thread "main" java.lang.UnsupportedOperationException: SSTable 'me-3gbr_0y9h_03n682utcozh4xc6c7-big-Data.db' is using the UUID-based identifier, and hence should be openned using 'scylla sstable' commands
        at org.apache.cassandra.io.sstable.Descriptor.fromFilename(Descriptor.java:295)
        at org.apache.cassandra.io.sstable.Descriptor.fromFilename(Descriptor.java:228)
        at org.apache.cassandra.io.sstable.Descriptor.fromFilename(Descriptor.java:217)
        at org.apache.cassandra.tools.SSTableMetadataViewer.main(SSTableMetadataViewer.java:150)
```

Fixes scylladb#360
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

src/java/org/apache/cassandra/io/sstable/Descriptor.java

@@ -277,7 +277,22 @@ public static Pair<Descriptor, String> fromFilename(File directory, String name,
         }
 
         // generation
-        int generation = Integer.parseInt(nexttok);
+        int generation;
+        try
+        {
+            // since Scylla 5.4, the SStable started using UUID v1 identifier
+            // instead of sequence of integers. but C* 3.x does not support the
+            // former. let's direct user to use the native tools of
+            // `scylla sstable` which is builtin in the scylla executable,
+            generation = Integer.parseInt(nexttok);
+        }
+        catch (NumberFormatException e)
+        {
+            throw new UnsupportedOperationException("SSTable '" + name
+                                                    + "' is using the UUID-based identifier, "
+                                                    + "and hence should be openned using "
+                                                    + "'scylla sstable' commands.");
+        }
 
         // version
         nexttok = tokenStack.pop();