Add lighthouse db command (#3129)

## Proposed Changes

Add a `lighthouse db` command with three initial subcommands:

- `lighthouse db version`: print the database schema version.
- `lighthouse db migrate --to N`: manually upgrade (or downgrade!) the database to a different version.
- `lighthouse db inspect --column C`: log the key and size in bytes of every value in a given `DBColumn`.

This PR lays the groundwork for other changes, namely:

- Mark's fast-deposit sync (https://github.com/sigp/lighthouse/pull/2915), for which I think we should implement a database downgrade (from v9 to v8).
- My `tree-states` work, which already implements a downgrade (v10 to v8).
- Standalone purge commands like `lighthouse db purge-dht` per https://github.com/sigp/lighthouse/issues/2824.

## Additional Info

I updated the `strum` crate to 0.24.0, which necessitated some changes in the network code to remove calls to deprecated methods.

Thanks to @winksaville for the motivation, and implementation work that I used as a source of inspiration (https://github.com/sigp/lighthouse/pull/2685).

beacon_node/src/config.rs

@@ -284,16 +284,7 @@ pub fn get_config<E: EthSpec>(
         client_config.freezer_db_path = Some(PathBuf::from(freezer_dir));
     }
 
-    if let Some(slots_per_restore_point) = cli_args.value_of("slots-per-restore-point") {
-        client_config.store.slots_per_restore_point = slots_per_restore_point
-            .parse()
-            .map_err(|_| "slots-per-restore-point is not a valid integer".to_string())?;
-    } else {
-        client_config.store.slots_per_restore_point = std::cmp::min(
-            E::slots_per_historical_root() as u64,
-            store::config::DEFAULT_SLOTS_PER_RESTORE_POINT,
-        );
-    }
+    client_config.store.slots_per_restore_point = get_slots_per_restore_point::<E>(cli_args)?;
 
     if let Some(block_cache_size) = cli_args.value_of("block-cache-size") {
         client_config.store.block_cache_size = block_cache_size
@@ -820,3 +811,17 @@ pub fn get_data_dir(cli_args: &ArgMatches) -> PathBuf {
         })
         .unwrap_or_else(|| PathBuf::from("."))
 }
+
+/// Get the `slots_per_restore_point` value to use for the database.
+pub fn get_slots_per_restore_point<E: EthSpec>(cli_args: &ArgMatches) -> Result<u64, String> {
+    if let Some(slots_per_restore_point) =
+        clap_utils::parse_optional(cli_args, "slots-per-restore-point")?
+    {
+        Ok(slots_per_restore_point)
+    } else {
+        Ok(std::cmp::min(
+            E::slots_per_historical_root() as u64,
+            store::config::DEFAULT_SLOTS_PER_RESTORE_POINT,
+        ))
+    }
+}

beacon_node/src/lib.rs

@@ -13,7 +13,7 @@ use beacon_chain::{
 use clap::ArgMatches;
 pub use cli::cli_app;
 pub use client::{Client, ClientBuilder, ClientConfig, ClientGenesis};
-pub use config::{get_config, get_data_dir, set_network_config};
+pub use config::{get_config, get_data_dir, get_slots_per_restore_point, set_network_config};
 use environment::RuntimeContext;
 pub use eth2_config::Eth2Config;
 use slasher::Slasher;