New VA108xx Rust workspace structure + dependency updates

- The workspace is now a monorepo without submodules. The HAL, PAC and BSP
  are integrated directly
- Update all dependencies: embedded-hal v1 and RTIC v2

va108xx-hal/src/prelude.rs

@@ -0,0 +1,3 @@
+//! Prelude
+pub use fugit::ExtU32 as _;
+pub use fugit::RateExtU32 as _;