feat: add helper functions to filter probes in lib

lib/default.nix

@@ -2,6 +2,18 @@
 rec {
   mkFqdn = _: cfg: cfg.networking.fqdn;
 
+  probesWithTag =
+    {
+      name,
+      value ? null,
+    }:
+    probesConfig:
+    lib.filterAttrs (
+      k: v: lib.any (tag: tag.name == name && (value == null || tag.value == value)) v.tags
+    ) probesConfig.monitors;
+
+  probesWithType = type: probesConfig: lib.filterAttrs (_: v: v.type == type) probesConfig.monitors;
+
   fromHive =
     {
       builder,