HPCC-11571 Always validate logical filenames

Ensure all filenames used in CDfsLogicalFileName are validated
Previously some formatting errors were caught, most not.
A seperate setValidate used different code which spotted some
errors and skipped others.

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
How to test the:
- removeForeign=true
- strict=true
in unit test?