Use frame-decode for core extrinsic decode logic (#1785)

* WIP using frame-decode for core extrinsic decode logic

* fmt

* Fix dependabot config

* clippy

* tidy some imports

* Fix a couple of tests

* Update to frame-decode 0.0.7

* fix docs

* Decode exts earlier to avoid doing it every iter/find step

* frame-decode to 0.1.0

* fmt

* clippy

* fix wasm example

* doc test fixes

* Fix test

* Fix a couple of subxt_core tests

.github/dependabot.yml

@@ -6,6 +6,7 @@ updates:
     schedule:
       interval: weekly
   - package-ecosystem: github-actions
-    directory: "**/*"
+    directories: 
+      - "**/*"
     schedule:
       interval: weekly