feat: add serde derive to Score types

This commit adds `serde` dependency and derives `Serialize` trait for `Score` types. This is necessary for serialization and deserialization of these types, which is required to display Scores to various user interfaces

- Added `serde` dependency to `harmony_types/Cargo.toml`.
- Added `serde::Serialize` derive macro to `MacAddress` in `harmony_types/src/lib.rs`.
- Added `serde::Serialize` derive macro to `Config` in `opnsense-config/src/config/config.rs`.
- Added `serde::Serialize` derive macro to `Score` in `harmony_types/src/lib.rs`.
- Added `serde::Serialize` derive macro to `Config` and `Score` in relevant modules.
- Added placeholder `todo!()` implementations for `serialize` methods. These will be implemented in future commits.

harmony/src/modules/dns.rs

@@ -1,6 +1,7 @@
 use async_trait::async_trait;
 use derive_new::new;
 use log::info;
+use serde::Serialize;
 
 use crate::{
     data::Version,
@@ -10,7 +11,7 @@ use crate::{
     topology::{DnsRecord, DnsServer, Topology},
 };
 
-#[derive(Debug, new, Clone)]
+#[derive(Debug, new, Clone, Serialize)]
 pub struct DnsScore {
     dns_entries: Vec<DnsRecord>,
     register_dhcp_leases: Option<bool>,