[cmake] Require CMake 3.16 or newer

This is related to core/dune-common!1302 (merged) which is related to or decision from the Dune developer meeting 2022, see https://dune-project.org/community/meetings/2022-02-devmeeting/#minimum-versions-of-gcc-clang-cmake-python

This MR is meant to keep the CMake version requirements in sync across multiple modules. Once the MR in dune-common is merged, this one should be merged, too.

changed the description

Can be merged after the corresponding branch in dune-common was merged.

added 5 commits

• a0c419ed...33aa9dd3 - 4 commits from branch master
• b613763a - [cmake] Require CMake 3.16 or newer

Compare with previous version

I merged this topic for the core modules. Shout be good be merged, too.

merged

mentioned in commit d2b45753