The 'IMPORT INTO' statement requires that the target table
be offline.  However, the current implementation does not have
functionality to ensure that if the target table has interleaved
children (or itself is interleaved in some other table), then those
tables are offline as well.

This change adds a check to ensure that an error is returned if
we attempt to IMPORT INTO interleaved table.

The future versions will support proper functionality to enable
IMPORT INTO interleaved tables.

Release justification: Prevent unsafe operation

Release note (cli): prevent INSERT INTO interleaved table.