HPCC-10298 CSV auto discovery should check the validity and uniqueness of the
discovered field name.

Add code for validate the filed name and check its uniqueness.
    All invalid character change to '_'.

    If fieldname isn't unique then add '_'+<field index>+'_'+<timestamp>
    postfix.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
HPCC-10298 CSV auto discovery should check the validity and uniqueness
of the discovered field name.

Add code for validate the filed name and check its uniqueness.
    All invalid character change to '_'.

    Use atom table to store fieldnames for checking.

    If fieldname isn't unique then add '_'+<field index>+'_'+<timestamp>
    postfix.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
HPCC-10298 CSV auto discovery should check the validity and uniqueness of
the discovered field name.

Fix field name uniqueness testing bug.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
Merge pull request #5428 from AttilaVamos/HPCC-10298-improvement

HPCC-10298 CSV auto discovery should check the validity and uniqueness of fields

Reviewed-By: Gavin Halliday <gavin.halliday@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>