MINOR: ssl/cli: support crt-list filters

MINOR: ssl/cli: support crt-list filters

Generate a list of the previous filters when updating a certificate
which use filters in crt-list. Then pass this list to the function
generating the sni_ctx during the commit.

This feature allows the update of the crt-list certificates which uses
the filters with "set ssl cert".

This function could be probably replaced by creating a new
ckch_inst_new_load_store() function which take the previous sni_ctx list as
an argument instead of the char **sni_filter, avoiding the
allocation/copy during runtime for each filter. But since are still
handling the multi-cert bundles, it's better this way to avoid code
duplication.