Update local testnet scripts, fix eth1 sim (#1184)

* Update local testnet scripts

* Add logs when decrypting validators

* Update comment

* Update account manager

* Make random key generation explicit

* Remove unnecessary clap constraint

* Only decrypt voting keypair for eth1 deposit

* Use insecure kdf for insecure keypairs

* Simplify local testnet keygen

* Update local testnet

* Fix eth1 sim

* Add eth1 sim to CI again

* Remove old local testnet docs

* Tidy

* Remove checks for existing validators

* Tidy

* Fix typos

scripts/local_testnet/README.md

@@ -0,0 +1,79 @@
+# Simple Local Testnet
+
+These scripts allow for running a small local testnet with two beacon nodes and
+one validator client. This setup can be useful for testing and development.
+
+## Requirements
+
+The scripts require `lci` and `lighthouse` to be installed on `PATH`. From the
+root of this repository, run:
+
+```bash
+cargo install --path lighthouse --force --locked
+cargo install --path lcli --force --locked
+```
+
+## Starting the testnet
+
+Assuming you are happy with the configuration in `var.env`, create the testnet
+directory, genesis state and validator keys with:
+
+```bash
+./setup
+```
+
+Start the first beacon node:
+
+```bash
+./beacon_node
+```
+
+In a new terminal, start the validator client which will attach to the first
+beacon node:
+
+```bash
+./validator_client
+```
+
+In a new terminal, start the second beacon node which will peer with the first:
+
+```bash
+./second_beacon_node
+```
+
+## Additional Info
+
+### Debug level
+
+The beacon nodes and validator client have their `--debug-level` set to `info`.
+Specify a different debug level like this:
+
+```bash
+./validator_client debug
+./beacon_node trace
+./second_beacon_node warn
+```
+
+### Starting fresh
+
+Delete the current testnet and all related files using:
+
+```bash
+./clean
+```
+
+
+### Updating the genesis time of the beacon state
+
+If it's been a while since you ran `./setup` then the genesis time of the
+genesis state will be far in the future, causing lots of skip slots.
+
+Update the genesis time to now using:
+
+```bash
+./reset_genesis_time
+```
+
+> Note: you probably want to drop the beacon node database and the validator
+> client slashing database if you do this. When using small validator counts
+> it's probably easy to just use `./clean && ./setup`.