Change genesis tools to create merged genesis by default

[parithosh]

• Updates Dockerfile to use protolambda's genesis-generator again
• Changes TTD and Merge fork block to 0
• Removes clique support as we do merged genesis
• Adds timestamp to EL genesis
• Modifies values.env to have more template values
• Updates entrypoint.sh

[skylenet]

Since ethereum has been merged already, this tool will start building the genesis state based on a PoS based network. This will facilitate testing for further ethereum forks.

If someone wants to test and generate testnets for pre-merge testnets and go through the merge again they'll have to use a previous version of the code. I've tagged the code just in case someone wants to find the right commit: https://github.com/skylenet/ethereum-genesis-generator/releases/tag/pre-merge

[gbouv]

@parithosh This env var does not appear in the values.env. Is that expected?

[parithosh]

Ah, I think i need to rename it to GENESIS_TIMESTAMP to keep it standard. Thank you!