HPCC-10150 Add support for relative imports using $.^.^.X

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10150 Clean up and add examples following code review.

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5348 from ghalliday/issue10150b

HPCC-10150 Add support for relative imports using $.^.^.X

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>