Restore workspace-wide clippy

Fixes accumulated errors in the Substrate code. Modifies the runtime build to
work with a modern clippy. Removes e2e tests from the workspace.

substrate/runtime/build.rs

@@ -1,5 +1,12 @@
 use substrate_wasm_builder::WasmBuilder;
 
 fn main() {
-  WasmBuilder::new().with_current_project().export_heap_base().import_memory().build()
+  WasmBuilder::new()
+    .with_current_project()
+    // https://substrate.stackexchange.com/questions/12124
+    // TODO: Remove once we've moved to polkadot-sdk
+    .disable_runtime_version_section_check()
+    .export_heap_base()
+    .import_memory()
+    .build()
 }