46340b3337 [bench] Add benchmark for unserialize prevector (Akio Nakamura)
Pull request description:
This PR adds benchmarks for the unserialization of the prevector.
Note: Separated from #12324.
Tree-SHA512: c055a283328cc2634c01eb60f26604a8665939bbf77d367b6ba6b4e01e77d4511fab69cc3ddb1e62969adb3c48752ed870f45ceba153eee192302601341e18a7