util: Rename `FilterHeaderHasher` to `Uint256Hasher` #98

Job	Run time
[meta] record frozen commit	4s
Windows native, VS 2022	1h 30m 2s
macOS native	42m 15s
macOS native, fuzz	24m 11s
Windows native, fuzz, VS 2022	54m 54s
[meta] determine runners	2s
test max 6 ancestor commits	0s
Windows-cross to x86_64, msvcrt	1h 0m 53s
Windows-cross to x86_64, ucrt	33m 25s
lint	5m 5s
No wallet	25m 27s
ASan + LSan + UBSan + integer	1h 6m 44s
macOS-cross to x86_64	28m 33s
iwyu	43m 13s
Valgrind, fuzz	4h 0m 19s
tidy	55m 18s
fuzzer,address,undefined,integer	3h 8m 26s
TSan	1h 11m 34s
Alpine (musl)	1h 38m 8s
i686, no IPC	51m 48s
MSan, fuzz	2h 18m 38s
macOS-cross to arm64	34m 3s
MSan	1h 12m 28s
previous releases	45m 23s
32 bit ARM	32m 56s
Windows, ucrt, test cross-built	47m 30s
Windows, msvcrt, test cross-built	45m 36s
	1d 2h 36m 55s

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