HPCC-12564 New regressionsuite option to generate multiple variants

- add code to handle multiple "//version <n1>=<v1>,<n2>=<v2>,..." tag in ECL file
- add code to generates stub(s) for ECl file if //version used conjuction with with //dynamic:source
- add code to make archive from generated stub
- change report code to mark //version tagged file with current parameters in output list
- update README.rst
- add a combined //dynamic and //version tag test to suite

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
HPCC-12564 New regressionsuite option to generate multiple variants

Update after review:
  - remove -dymanic command line parameter and handler
  - remove //dynamic tag handler
  - remove dynamicsource_tag.ecl and xml
  - remove issue12565.ecl and xml
  - update README.rst

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
Merge pull request #6658 from AttilaVamos/HPCC-12564-improvement

HPCC-12564 New regressionsuite option to generate multiple variants

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>