* trie: add node type common package
In trie/types package, a few node wrappers are defined, which will be used
in both trie package, trie/snap package, etc. Therefore, a standalone common
package is created to put these stuffs.
* trie: rename trie/types to trie/trienode
Co-authored-by: rjl493456442 <garyrong0905@gmail.com>
