docs: kdoc: use tokenizer to handle comments on structs

docs: kdoc: use tokenizer to handle comments on structs

Better handle comments inside structs. After those changes,
all unittests now pass:

  test_private:
    TestPublicPrivate:
        test balanced_inner_private:                                 OK
        test balanced_non_greddy_private:                            OK
        test balanced_private:                                       OK
        test no private:                                             OK
        test unbalanced_inner_private:                               OK
        test unbalanced_private:                                     OK
        test unbalanced_struct_group_tagged_with_private:            OK
        test unbalanced_two_struct_group_tagged_first_with_private:  OK
        test unbalanced_without_end_of_line:                         OK

  Ran 9 tests

This also solves a bug when handling STRUCT_GROUP() with a private
comment on it:

	@@ -397134,7 +397134,7 @@ basic V4L2 device-level support.
	             unsigned int    max_len;
	             unsigned int    offset;
	             struct page_pool_params_slow  slow;
	-            STRUCT_GROUP( struct net_device *netdev;
	+            struct net_device *netdev;
	             unsigned int queue_idx;
	             unsigned int    flags;
	       };

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Message-ID: <f83ee9e8c38407eaab6ad10d4ccf155fb36683cc.1773074166.git.mchehab+huawei@kernel.org>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <054763260f7b5459ad0738ed906d7c358d640692.1773770483.git.mchehab+huawei@kernel.org>