Make custom FIPS-202 headers configurable #4801

Job	Run time
Quickcheck (aarch64)	46s
Quickcheck (x86_64)	1m 26s
Quickcheck C90 (aarch64)	1m 6s
Quickcheck (macos (aarch64))	1m 17s
lint-markdown-link	38s
Quickcheck C90 (x86_64)	1m 26s
Linting (ubuntu-latest)	1m 25s
Quickcheck (macos (x86_64))	1m 25s
Linting (pqcp-arm64)	48s
Quickcheck windows-latest	37s
Check API consistency (false, pqcp-arm64, aarch64)	32s
Quickcheck lib (macos-latest)	12s
Check API consistency (false, ubuntu-latest, x86_64)	49s
Quickcheck windows-2022	36s
Quickcheck lib (macos-13)	27s
Quickcheck lib (ubuntu-latest)	17s
Quickcheck windows-2019	34s
Examples (macos-latest)	15s
Examples (macos-13)	29s
Examples (ubuntu-latest)	11s
Quickcheck lib (pqcp-arm64)	32s
Examples (pqcp-arm64)	7s
AArch64 dev backend (Clean, Simplified)	36s
AArch64 dev backend (Clean, Unmodified)	35s
AArch64 dev backend (Optimized, Simplified)	1s
AArch64 dev backend (Optimized, Unmodified)	19s
Functional tests (${{ matrix.target.arch }}${{ (((matrix.target.mode != 'native') && ', cross') \|\| '') }})	1s
Check autogenerated files	1s
Non-standard configurations	1s
Compiler tests (${{ matrix.compiler.name }}, ${{ matrix.target.name }})	1s
Compatibility tests (${{ matrix.container.id }})	1s
CBMC (ML-KEM-512)	1s
Compatibility tests (${{ matrix.container.id }})	1s
Platform tests (${{ matrix.target.name }})	1s
CBMC (ML-KEM-768)	1s
CBMC (ML-KEM-1024)	1s
	17m 36s

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