This PR moves some trie-related db accessor methods to a different file, and also removes the schema type. Instead of the schema type, a string is used to distinguish between hashbased/pathbased db accessors.
This also moves some code from trie package to rawdb package.

This PR is intended to be a no-functionality-change prep PR for #25963 .

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Co-authored-by: Gary Rong <garyrong0905@gmail.com>