Support for ERA (not ERA1) hosts in the downloader

[RomanHodulak]

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Describe the feature

Currently, the reth_era_downloader can deal with ERA1 hosts.

https://github.com/paradigmxyz/reth/blob/9ab57f70e3e5686b59a6f93fc41363d46707de73/crates/era-downloader/Cargo.toml#L2

The goal is to add support for ERA (not ERA1) hosts.

One notable difference is that compared to ERA1 hosts, these don't tend to contain checksums.txt, which is unfortunate as it makes file integrity checks impossible.

Another one is that, of course, the file format is different. However, the downloader is not dealing with the encoding at all, so this is not a concern.

Additional context

No response

[github-actions[bot]]

This issue is stale because it has been open for 21 days with no activity.

[lean-apple]

@mattsse, @RomanHodulak, for this issue, would it be possible to also host https://era.ithaca.xyz/era/index.html (from https://mainnet.era.nimbus.team/), and for testnet, maybe the hoodi one https://era.ithaca.xyz/hoodi-era/ (from https://hoodi.era.nimbus.team/) The sepolia one was like this https://era.ithaca.xyz/sepolia-era1/index.html, we can also do the sepolia one like https://sepolia.era.nimbus.team/.