fuzz: Move implementations of non-template fuzz helpers from util.h to util.cpp #22445

There are 78 cpp files that include util.h (grep -iIr "#include <test/fuzz/util.h>" src/test/fuzz | wc -l). Modifying the implementation of a fuzz helper in src/test/fuzz/util.h will cause all fuzz tests to be recompiled. Keeping the declarations of these non-template fuzz helpers in util.h and moving their implementations to util.cpp will skip the redundant recompilation of all the fuzz tests, and builds these helpers only once in util.cpp.

Functions moved from util.h to util.cpp:

• ConsumeTxMemPoolEntry
• ContainsSpentInput
• ConsumeNetAddr
• Methods of FuzzedFileProvider::(open, read, write, seek, close)

utACK 6abf29492fba1408c874972e7c0e2afc4d84501e

Nice. Concept ACK.

Please squash your commits according to https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md#squashing-commits

Concept ACK

review ACK a2aca207b1ad00ec05d7533dbd75bbff830e1d75 🍂

reviewed with: git show a2aca207b1ad00ec05d7533dbd75bbff830e1d75 --color-moved=dimmed-zebra --color-moved-ws=ignore-all-space

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review ACK a2aca207b1ad00ec05d7533dbd75bbff830e1d75 🍂

reviewed with:
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Timestamp of file with hash a68bd1199081ef367925d3f633cddc5d34c485b33bbba693b151eb7f0eb39a95 -

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