Merge rust-bitcoin/rust-secp256k1#743: Make `RecoveryId` an enum #1454

Job	Run time
Docs - stable toolchain (recent)	13s
Test - 1.63.0 toolchain (minimal)	4m 25s
Test 32-bit version	24s
Test - 1.63.0 toolchain (recent)	4m 23s
Format - nightly toolchain	12s
Prepare	2s
Test - stable toolchain (minimal)	3m 39s
WASM - stable toolchain	1m 43s
Test - stable toolchain (recent)	3m 24s
ASAN - nightly toolchain (recent)	1m 29s
Docs - nightly toolchain (recent)	39s
Lint - nightly toolchain (recent)	27s
Bench - nightly toolchain (recent)	26s
Test - nightly toolchain (minimal)	2m 43s
no-std - nightly toolchain (recent)	40s
Test - nightly toolchain (recent)	2m 30s
	27m 19s

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