modules/prometheus: split exporters and alerts to seperate files

modules/nixos/prometheus/gotosocial.nix

@@ -0,0 +1,19 @@
+{ config, lib, ... }:
+let
+  cfg = config.custom.prometheus;
+in
+{
+  config = lib.mkIf cfg.exporters.gotosocial.enable {
+    services.gotosocial.settings = lib.mkIf cfg.exporters.gotosocial.enable {
+      metrics-enabled = true;
+    };
+    services.prometheus.scrapeConfigs = [
+      {
+        job_name = "gotosocial";
+        static_configs = [
+          { targets = [ "localhost:8080" ]; }
+        ];
+      }
+    ];
+  };
+}