elliptic_curve: add `BatchInvert` and `BatchNormalize` traits #2401

Job	Run time
doc	14s
build (1.65.0, thumbv7em-none-eabi)	6m 5s
minimal-versions	20s
build (1.65.0, wasm32-unknown-unknown)	4m 1s
test (1.65.0)	3m 45s
build (stable, thumbv7em-none-eabi)	37s
test (stable)	30s
build (stable, wasm32-unknown-unknown)	50s
test (nightly)	42s
	17m 4s

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