This PR updates the CMake build/install docs in `docs/INSTALL-CMAKE.md`,
in particular focusing on the use of libcurl from CMake using
`find_package` as well as the newly added features/protocols support via
using `COMPONENTS` or `OPTIONAL_COMPONENTS` with `find_package`.
See #15854 for initial discussion and the corresponding PR #15858 that
was merged.
Some additional best-practices notes are added, for example:
* Encouraging building out-of-source
* Using `--config` with `cmake --build` for multi-config CMake
generators, not `CMAKE_BUILD_TYPE`
We also add a CURL CMake-specific tip on using `CMAKE_INSTALL_PREFIX`
during configure time to set the install prefix, not using `--prefix`
when running `cmake --install` so `curl-config` output is consistent.
Closes#16329
af0100fc17