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/database/config.rs

@@ -0,0 +1,74 @@
+use serde::{Deserialize, Serialize};
+
+pub const USER: &str = "postgres";
+pub const PASSWORD: &str = "postgres";
+pub const DBNAME: &str = "dev";
+pub const DEFAULT_DBNAME: &str = "postgres";
+pub const HOST: &str = "localhost";
+pub const fn port() -> u16 {
+    5432
+}
+pub const fn connect_timeout_millis() -> u64 {
+    2_000 // 2s
+}
+
+fn user() -> String {
+    USER.to_string()
+}
+
+fn password() -> String {
+    PASSWORD.to_string()
+}
+
+fn dbname() -> String {
+    DBNAME.to_string()
+}
+
+fn default_dbname() -> String {
+    DEFAULT_DBNAME.to_string()
+}
+
+fn host() -> String {
+    HOST.to_string()
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Config {
+    #[serde(default = "user")]
+    pub user: String,
+    #[serde(default = "password")]
+    pub password: String,
+    #[serde(default = "dbname")]
+    pub dbname: String,
+    #[serde(default = "default_dbname")]
+    pub default_dbname: String,
+    #[serde(default = "host")]
+    pub host: String,
+    #[serde(default = "port")]
+    pub port: u16,
+    #[serde(default = "connect_timeout_millis")]
+    pub connect_timeout_millis: u64,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {
+            user: user(),
+            password: password(),
+            dbname: dbname(),
+            default_dbname: default_dbname(),
+            host: host(),
+            port: port(),
+            connect_timeout_millis: connect_timeout_millis(),
+        }
+    }
+}
+
+impl Config {
+    pub fn build_database_url(&self) -> String {
+        format!(
+            "postgres://{}:{}@{}:{}/{}",
+            self.user, self.password, self.host, self.port, self.dbname
+        )
+    }
+}