[pallet-revive] eth-rpc minor fixes (#7325)

- Add option to specify database_url using DATABASE_URL environment
variable
- Add a eth-rpc-tester rust bin that can be used to test deployment
before releasing eth-rpc
- make evm_block non fallible so that it can return an Ok response for
older blocks when the runtime API is not available
- update cargo.lock to integrate changes from
https://github.com/paritytech/subxt/pull/1904

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