cmakelists changes

[shengjianda]

1. add prefix for options
2. auto create metis.h from metis.h.in depends on cmake setting of METIS_IDX64 and METIS_REAL64,
3. metis can be used as submodule for other projects

[LecrisUT]

Hey @shengjianda I have some pointers about CMake modernization. Can we collaborate a bit to make this project more usable? I will submit a few PRs on your forks with

• Github Actions so that we can validate the builds a bit
• Update the minimum requirement to at least 3.11 to use FetchContent (technically we should go for 3.24 to make use of FIND_PACKAGE_ARGS, but I have a simple backport for that that we can use)
• Add CMake packaging
• General reorganization to make things readable (see my approach in the spglib and octopus packaging)

See #79. Working on the equivalent for GKlib tomorrow