Add beacon.watch (#3362)

> This is currently a WIP and all features are subject to alteration or removal at any time.

## Overview

The successor to #2873.

Contains the backbone of `beacon.watch` including syncing code, the initial API, and several core database tables.

See `watch/README.md` for more information, requirements and usage.

watch/src/config.rs

@@ -0,0 +1,50 @@
+use crate::blockprint::Config as BlockprintConfig;
+use crate::database::Config as DatabaseConfig;
+use crate::server::Config as ServerConfig;
+use crate::updater::Config as UpdaterConfig;
+
+use serde::{Deserialize, Serialize};
+use std::fs::File;
+
+pub const LOG_LEVEL: &str = "debug";
+
+fn log_level() -> String {
+    LOG_LEVEL.to_string()
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Config {
+    #[serde(default)]
+    pub blockprint: BlockprintConfig,
+    #[serde(default)]
+    pub database: DatabaseConfig,
+    #[serde(default)]
+    pub server: ServerConfig,
+    #[serde(default)]
+    pub updater: UpdaterConfig,
+    /// The minimum severity for log messages.
+    #[serde(default = "log_level")]
+    pub log_level: String,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {
+            blockprint: BlockprintConfig::default(),
+            database: DatabaseConfig::default(),
+            server: ServerConfig::default(),
+            updater: UpdaterConfig::default(),
+            log_level: log_level(),
+        }
+    }
+}
+
+impl Config {
+    pub fn load_from_file(path_to_file: String) -> Result<Config, String> {
+        let file =
+            File::open(path_to_file).map_err(|e| format!("Error reading config file: {:?}", e))?;
+        let config: Config = serde_yaml::from_reader(file)
+            .map_err(|e| format!("Error parsing config file: {:?}", e))?;
+        Ok(config)
+    }
+}