feat: automatically discover inventory (#127)

## Fully automated inventory gathering now works!

Boot up harmony_inventory_agent with `cargo run -p harmony_inventory_agent`
Launch the DiscoverInventoryAgentScore , currently available this way :

`RUST_LOG=info cargo run -p example-cli -- -f Discover -y`

And you will have automatically all hosts saved to the database. Run `cargo sqlx setup` if you have not done it yet.

Co-authored-by: Ian Letourneau <ian@noma.to>
Reviewed-on: NationTech/harmony#127
Co-authored-by: Jean-Gabriel Gill-Couture <jg@nationtech.io>
Co-committed-by: Jean-Gabriel Gill-Couture <jg@nationtech.io>

harmony_inventory_agent/src/client.rs

@@ -0,0 +1,15 @@
+use crate::hwinfo::PhysicalHost;
+
+pub async fn get_host_inventory(host: &str, port: u16) -> Result<PhysicalHost, String> {
+    let url = format!("http://{host}:{port}/inventory");
+    let client = reqwest::Client::new();
+    let response = client
+        .get(url)
+        .send()
+        .await
+        .map_err(|e| format!("Failed to download file: {e}"))?;
+
+    let host = response.json().await.map_err(|e| e.to_string())?;
+
+    Ok(host)
+}