- replace `add_compile_options()`, `add_definitions()` with directory
properties. To harmonize this across all scripts. The new commands are
verbose, but describe better how they work. The syntax is also closer
to setting target properties, helps grepping.
- prefer `CMAKE_INSTALL_PREFIX` over `--prefix` (in tests, CI).
- tidy up cmake invocations.
- formatting.
Closes#16238
Add CMake test project consuming curl via these methods:
`FetchContent`, `add_subdirectory()`, `find_package()`.
Also:
- GHA/distcheck: run these tests in CI.
- cmakelint: exclude a warning for calling "wonky-cased" built-in
CMake functions, such as `FetchContent_Declare()`.
Closes#16126
