evaluate: check if table and chain exists when adding rules

evaluate: check if table and chain exists when adding rules

Assuming a table 'test' that contains a chain 'test':

 # nft add rule test1 test2 counter
 <cmdline>:1:1-28: Error: Could not process rule: Table 'test1' does not exist
 add rule test1 test2 counter
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 # nft add rule test test2 counter
 <cmdline>:1:1-27: Error: Could not process rule: Chain 'test2' does not exist
 add rule test test2 counter
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^

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