Add sudo::remove_key (#2165)

Changes:
- Adds a new call `remove_key` to the sudo pallet to permanently remove
the sudo key.
- Remove some clones and general maintenance

---------

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: command-bot <>

prdoc/pr_2165.prdoc

@@ -0,0 +1,17 @@
+title: Add sudo::remove_key
+
+doc:
+  - audience: Core Dev
+    description: |
+      Pallet `Sudo` now has the ability to remove the sudo key via `remove_key`. This is a less-invasive way of rendering the sudo pallet useless without needing a code upgrade.
+
+migrations:
+  db: []
+
+  runtime: []
+
+crates:
+  - name: pallet-sudo
+    semver: minor
+
+host_functions: []