Use the new code_props interface for rule actions.

* src/symlist.h (symbol_list): Replace action, action_location, and
used members with a code_props action_props member.
* src/reader.c (symbol_should_be_used, grammar_rule_check,
grammar_midrule_action, grammar_current_rule_merge_set,
grammar_current_rule_symbol_append, packgram): Update.
* src/scan-code.h (translate_rule_action): Remove, no longer used.
* src/scan-code.l (handle_action_dollar): Update.
(translate_rule_action): Remove, no longer used.
* src/symlist.c (symbol_list_sym_new, symbol_list_syms_print): Update.