Rename embassy-hal-common to embassy-hal-internal, document it's for internal use only. (#1700)

embassy-hal-internal/src/lib.rs

@@ -0,0 +1,17 @@
+#![no_std]
+#![allow(clippy::new_without_default)]
+#![doc = include_str!("../README.md")]
+
+// This mod MUST go first, so that the others see its macros.
+pub(crate) mod fmt;
+
+pub mod atomic_ring_buffer;
+pub mod drop;
+mod macros;
+mod peripheral;
+pub mod ratio;
+pub mod ring_buffer;
+pub use peripheral::{Peripheral, PeripheralRef};
+
+#[cfg(feature = "cortex-m")]
+pub mod interrupt;