Faucet setup for funding test accounts

[spypsy]

we currently have a lot of accounts funded from a mnemonic that will need to be assigned for each task we run on Sepolia (e.g. accounts 1-50 for zombie chain, 51-54 for e2e test etc)
this isn't very manageable if we want to start running multiple tests at the same time, especially now that e2e test is part of CI.
Need a setup where a main Sepolia account acts as faucet and then funds accounts according to needs, using mnemonic.

e.g. for e2e test:

1. Create new mnemonic
2. Take 5 first accounts derived from it

• 3 validators
• 1 contract deployer
• 1 prover

3. Run test
4. Refund main account