Workaround std::gcd and std::lcm constexpr issue

[AlexanderSinn]

It seems that std::gcd and std::lcm are not fully constexpr on some platforms, so this PR replaces the general formular with a simplified version that produces the same result, assuming that alignof(int) = 4 and alignof(amrex::Real) = 4 or 8.

• Small enough (< few 100s of lines), otherwise it should probably be split into smaller PRs
• Tested (describe the tests in the PR description)
• Runs on GPU (basic: the code compiles and run well with the new module)
• Contains an automated test (checksum and/or comparison with theory)
• Documented: all elements (classes and their members, functions, namespaces, etc.) are documented
• Constified (All that can be const is const)
• Code is clean (no unwanted comments, )
• Style and code conventions are respected at the bottom of https://github.com/Hi-PACE/hipace
• Proper label and GitHub project, if applicable

[MaxThevenet]

Thanks for this PR! This was tested by a user and fixes the issue indeed.