## Issue Addressed
NA
## Proposed Changes
This PR adds some more fancy macro magic to make it easier to add a new built-in (aka "baked-in") testnet config to the `lighthouse` binary.
Previously, a user needed to modify several files and repeat themselves several times. Now, they only need to add a single definition in the `eth2_config` crate. No repetition 🎉
## Proposed Changes
Implement the consensus changes necessary for the upcoming Altair hard fork.
## Additional Info
This is quite a heavy refactor, with pivotal types like the `BeaconState` and `BeaconBlock` changing from structs to enums. This ripples through the whole codebase with field accesses changing to methods, e.g. `state.slot` => `state.slot()`.
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Issue Addressed
Replaces #2091
## Proposed Changes
* Delete the uncompressed genesis states from `eth2_network_config` after they were merged accidentally in #2029.
* Tweak the build script to not overwrite `genesis.ssz` on every build, which caused spurious rebuilds.
## Issue Addressed
#1992 and #1987, and also to be considered a continuation of #1751
## Proposed Changes
many changed files but most are renaming to align the code with the semantics of `--network`
- remove the `--network` default value (in clap) and instead set it after checking the `network` and `testnet-dir` flags
- move `eth2_testnet_config` crate to `eth2_network_config`
- move `Eth2TestnetConfig` to `Eth2NetworkConfig`
- move `DEFAULT_HARDCODED_TESTNET` to `DEFAULT_HARDCODED_NETWORK`
- `beacon_node`s `get_eth2_testnet_config` loads the `DEFAULT_HARDCODED_NETWORK` if there is no network nor testnet provided
- `boot_node`s config loads the config same as the `beacon_node`, it was using the configuration only for preconfigured networks (That code is ~1year old so I asume it was not intended)
- removed a one year old comment stating we should try to emulate `https://github.com/eth2-clients/eth2-testnets/tree/master/nimbus/testnet1` it looks outdated (?)
- remove `lighthouse`s `load_testnet_config` in favor of `get_eth2_network_config` to centralize that logic (It had differences)
- some spelling
## Additional Info
Both the command of #1992 and the scripts of #1987 seem to work fine, same as `bn` and `vc`
