Update testnet configs, change on-disk format (#1799)

## Issue Addressed

- Related to #1691

## Proposed Changes

- Add `DEPOSIT_CHAIN_ID` and `DEPOSIT_NETWORK_ID` to `config.yaml`.
    - Pass the `DEPOSIT_NETWORK_ID` to the `eth1::Service`.
- Remove the unused `MAX_EPOCHS_PER_CROSSLINK` from the `altona` and `medalla` configs (see [spec commit](2befe90032 (diff-efb845ac2ebd4aafbc23df40f47ce25699255064e99d36d0406d0a14ca7953ec))).
- Change from compressing the whole testnet directory, to only compressing the genesis state file. This is the only file we need to compress and *not* compressing the others makes them work nicely with git.
    - We can modify the boot nodes, configs, etc. without incurring an eternal binary-blob cost on our git history.
    - This change is backwards compatible (i.e., non-breaking).

## Additional Info

NA

common/eth2_config/src/lib.rs

@@ -3,6 +3,18 @@ use std::env;
 use std::path::PathBuf;
 use types::ChainSpec;
 
+// A macro is used to define this constant so it can be used with `include_bytes!`.
+#[macro_export]
+macro_rules! testnets_dir {
+    () => {
+        "built_in_testnet_configs"
+    };
+}
+
+pub const TESTNETS_DIR: &str = testnets_dir!();
+pub const GENESIS_FILE_NAME: &str = "genesis.ssz";
+pub const GENESIS_ZIP_FILE_NAME: &str = "genesis.ssz.zip";
+
 /// The core configuration of a Lighthouse beacon node.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(default)]
@@ -51,33 +63,23 @@ impl Eth2Config {
 pub struct Eth2NetArchiveAndDirectory<'a> {
     pub name: &'a str,
     pub unique_id: &'a str,
-    pub archive_name: &'a str,
     pub genesis_is_known: bool,
 }
 
 impl<'a> Eth2NetArchiveAndDirectory<'a> {
     /// The directory that should be used to store files downloaded for this net.
-    fn pwd(&self) -> PathBuf {
+    pub fn dir(&self) -> PathBuf {
         env::var("CARGO_MANIFEST_DIR")
             .expect("should know manifest dir")
             .parse::<PathBuf>()
             .expect("should parse manifest dir as path")
+            .join(TESTNETS_DIR)
+            .join(self.unique_id)
     }
 
-    pub fn dir(&self) -> PathBuf {
-        self.pwd().join(self.unique_id)
+    pub fn genesis_state_archive(&self) -> PathBuf {
+        self.dir().join(GENESIS_ZIP_FILE_NAME)
     }
-
-    pub fn archive_fullpath(&self) -> PathBuf {
-        self.pwd().join(self.archive_name)
-    }
-}
-
-#[macro_export]
-macro_rules! unique_id {
-    ($name: tt) => {
-        concat!("testnet_", $name);
-    };
 }
 
 macro_rules! define_net {
@@ -88,8 +90,7 @@ macro_rules! define_net {
 
             pub const ETH2_NET_DIR: Eth2NetArchiveAndDirectory = Eth2NetArchiveAndDirectory {
                 name: $name,
-                unique_id: unique_id!($name),
-                archive_name: concat!(unique_id!($name), ".zip"),
+                unique_id: $name,
                 genesis_is_known: $genesis_is_known,
             };
 
@@ -98,7 +99,15 @@ macro_rules! define_net {
             #[macro_export]
             macro_rules! $macro_title {
                 ($base_dir: tt, $filename: tt) => {
-                    include_bytes!(concat!($base_dir, unique_id!($name), "/", $filename))
+                    include_bytes!(concat!(
+                        $base_dir,
+                        "/",
+                        testnets_dir!(),
+                        "/",
+                        $name,
+                        "/",
+                        $filename
+                    ))
                 };
             }
         }