parser: remove the "new" and "destroy" tokens from the scanner

parser: remove the "new" and "destroy" tokens from the scanner

These new tokens were introduced in f9563c0 ("src: add events reporting")
to allow filtering based on the event type.

This confuses the parser when parsing the "new" token:

test:32:33-35: Error: syntax error, unexpected new
add rule filter output ct state new,established counter
                                ^^^

This patch fixes this by replacing these event type tokens by the
generic string token, which is then interpreted during the parsing.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>