* indexer: clean up duplicated code

Remove `ParseL1Address` and `ParseL2Address` and
instead use `ParseAddress`. Addresses on L1 and L2
are the same and we can use as much upstream code
as possible instead of code from `l2geth`.

* Update indexer/crypto.go
Co-authored-by: Javed Khan <javed@optimism.io>
Co-authored-by: Javed Khan <javed@optimism.io>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>