feat: add StaticFileSegment::AccountChangeSets

[Rjected]

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ref https://github.com/paradigmxyz/reth/issues/18846

Introduces a new flag --db.enable-v2-static-files which controls whether or not we should write account changesets to static files or the DB.

Adds account changesets as a new static file segment, where each row is a change. This makes them different from "block-based" static files like headers, and "transaction-based" static files like transactions and receipts. Row ranges for each block are stored in the header for the static file segment.

Backwards compat deserialization code is added because this adds fields to the static file header.