Here is a draft for the New EraE implementation. The code follows along
with the spec listed at https://hackmd.io/pIZlxnitSciV5wUgW6W20w.
---------
Co-authored-by: shantichanal <158101918+shantichanal@users.noreply.github.com>
Co-authored-by: lightclient <lightclient@protonmail.com>
Co-authored-by: MariusVanDerWijden <m.vanderwijden@live.de>
Co-authored-by: Sina Mahmoodi <itz.s1na@gmail.com>
This adds a geth subcommand for downloading era1 files and placing them into
the correct location. The tool can be used even while geth is already running
on the datadir. Downloads are checked against a hard-coded list of checksums
for mainnet and sepolia.
```
./geth download-era --server $SERVER --block 333333
./geth download-era --server $SERVER --block 333333-444444
./geth download-era --server $SERVER --epoch 0-10
./geth download-era --server $SERVER --all
```
The implementation reuses the file downloader we already had for
fetching build tools. I've done some refactoring on it to make sure it
can support the new use case, and there are some changes to the build
here as well.
