Split usb_report_descriptor into usb_hid_{item,usage}

This is cleaner IMO.

* usb_hid_item deals with parsing the report descriptor.
* usb_hid_usage has tables that define each usage.

usb_hid_usage/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "usb_hid_usage"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]