HPCC-8804 New ECL Watch homepage

Add new Activity page.
Add new Search Results page.
Enhance ensureNavLink to allow opening in a new page.
Add links to legacy pages.

Fixes HPCC-8804

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #4582 from GordonSmith/HPCC-8804

HPCC-8804 New ECL Watch homepage

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>