Implement instance info endpoint (JSON, YAML, TXT) (#685)

Co-authored-by: Daniel Valentine <daniel@vielle.ws>
Co-authored-by: spikecodes <19519553+spikecodes@users.noreply.github.com>

build.rs

@@ -0,0 +1,20 @@
+use std::{
+	os::unix::process::ExitStatusExt,
+	process::{Command, ExitStatus, Output},
+};
+fn main() {
+	let output = String::from_utf8(
+		Command::new("git")
+			.args(["rev-parse", "HEAD"])
+			.output()
+			.unwrap_or(Output {
+				stdout: vec![],
+				stderr: vec![],
+				status: ExitStatus::from_raw(0),
+			})
+			.stdout,
+	)
+	.unwrap_or_default();
+	let git_hash = if output == String::default() { "dev".into() } else { output };
+	println!("cargo:rustc-env=GIT_HASH={git_hash}");
+}