FindHighFive Rewrite, main branch (2025.03.24.)

Stopped using HighFive's own CMake code in our FindHighFive.cmake module. This is to avoid the non-trivial setup that comes with HighFive 2.10.1. 🤔

I do not consider this a perfect solution by a long shot. But the HighFive CMake code is just a bit too awkward to make work in the ATLAS build environment. ☹️

This is related to all the following tickets: SPI-2757, SPI-2753, ATLINFR-5716.