A partial patch for MDEV-12518 Unify sql_yacc.yy and sql_yacc_ora.yy

Making sql_yacc.yy close to sql_yacc_ora.yy:

1. Adding struct sp_cursor_name_and_offset into %union
2. Adding field_type_numeric, field_type_string,  field_type_lob,
   field_type_temporal, field_type_misc
3. Adding keyword_sp_data_type and keyword_sp_not_data_type
4. Removing "opt_savepoint". Moving this grammar to "rollback" instead.
   This fixes one shift/reduce conflict.
5. Minor indentation cleanup.

sql/sql_yacc_ora.yy

@@ -14720,7 +14720,7 @@ keyword_sp:
 
 /*
   These keywords are generally allowed as identifiers,
-  but not allowed as non-delimited SP variable names.
+  but not allowed as non-delimited SP variable names in sql_mode=ORACLE.
 */
 keyword_sp_data_type:
           BIT_SYM                  {}
@@ -15278,7 +15278,7 @@ option_value_no_option_type:
             if (Lex->init_default_internal_variable(&var, $3) ||
                 Lex->set_variable(&var, $5))
               MYSQL_YYABORT;
-           }
+          }
         | '@' ident_or_text equal expr
           {
             Item_func_set_user_var *item;