Add NIST P curve support to ECDH #649

Job	Run time
Check wasm targets (nightly-2024-02-07)	44s
Build and test (Nix) (ubuntu-latest, nightly-2024-02-07)	5m 59s
Check wasm targets (beta)	45s
Build and test (Windows) (windows-latest, nightly-2024-02-07, x86_64-pc-windows-gnu)	5m 53s
Build and test (Nix) (ubuntu-latest, beta)	5m 59s
Check wasm targets (stable)	50s
clippy_check	1m 30s
Build and test (Windows) (windows-latest, beta, x86_64-pc-windows-gnu)	5m 54s
Build and test (Nix) (ubuntu-latest, stable)	5m 11s
Build and test (Windows) (windows-latest, stable, x86_64-pc-windows-gnu)	5m 57s
Build and test (Nix) (macOS-latest, nightly-2024-02-07)	5m 59s
codespell	12s
Cross compile (i686-unknown-linux-gnu)	6m 11s
Build and test (Nix) (macOS-latest, beta)	6m 0s
Cross compile (powerpc-unknown-linux-gnu)	6m 11s
Build and test (Nix) (macOS-latest, stable)	6m 0s
Cross compile (arm-linux-androideabi)	6m 12s
Checking fmt and docs	1m 40s
	1h 17m 7s

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