elliptic-curve: add missing `Debug` impls (#1675) #2224

Job	Run time
minimal-versions	0s
no_std (1.75.0, thumbv7em-none-eabi)	11s
test (1.75.0)	18s
no_std (1.75.0, wasm32-unknown-unknown)	13s
test (stable)	19s
no_std (stable, thumbv7em-none-eabi)	15s
no_std (stable, wasm32-unknown-unknown)	11s
	1m 27s

Provide feedback