feat: drop ExEx WAL on `reth db drop`

[0xurb]

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Possible solutions:

1. Since we are use reth db drop primary as a re-sync, so I think we can drop not only db & static files, but WAL also.
2. Another option is reth exex - exex CLI subcommand to fully operate the WAL and future things around ExEx control.

This PR contains (1) approach.