split the fmt rule into fmt-check and fmt (dragoon/komodo!46)

this MR splits the `fmt` rule of the `Makefile` into `fmt-check` and `fmt`, where `fmt` does the actual formatting and `fmt-check` only checks for bad format.

Makefile

-.PHONY: fmt check clippy test example show
+.PHONY: fmt fmt-check check clippy test example show
 
-DEFAULT_GOAL: fmt check clippy test
+DEFAULT_GOAL: fmt-check check clippy test
 
-fmt:
+fmt-check:
 	cargo fmt --all -- --check
 
+fmt:
+	cargo fmt --all
+
 check:
 	cargo check --workspace --all-targets