feat(sources): add custom auth strategy for components with HTTP server

changelog.d/22236_custom_server_auth_strategy.breaking.md

@@ -0,0 +1,8 @@
+Custom authorization strategy is now supported for sources running
+HTTP servers (`http_server` source, `prometheus` source, `datadog_agent`, etc.).
+
+Since there are now multiple authorization strategies, if you are using `auth` in any
+of these supported components, you now also need to add `strategy: "basic"`, together with
+`user` and `password`.
+
+authors: esensar

src/sources/util/http/error.rs → src/common/http/error.rs

@@ -1,3 +1,4 @@
+#![allow(missing_docs)]
 use std::{error::Error, fmt};
 
 use serde::Serialize;

src/common/http/mod.rs

@@ -0,0 +1,12 @@
+//! Common module between modules that use HTTP
+#[cfg(all(
+    feature = "sources-utils-http-auth",
+    feature = "sources-utils-http-error"
+))]
+pub mod server_auth;
+
+#[cfg(feature = "sources-utils-http-error")]
+mod error;
+
+#[cfg(feature = "sources-utils-http-error")]
+pub use error::ErrorMessage;