This commit updates various CMake configuration files to simplify
the check for Apple platforms. It replaces the `CMAKE_CXX_COMPILER_ID`
check for `AppleClang` with the built-in `APPLE` variable across
multiple targets (such as `ftd`, `mtd`, `cli`, and others). This
ensures that Apple-specific linker and compiler flags (like `-Wl,-map`
and `-Wimplicit-int-conversion`) are correctly applied when building
on macOS, regardless of the specific compiler used.
Additionally, this commit updates `CMakeLists.txt` to explicitly set
the `CMAKE_AR` and `CMAKE_RANLIB` paths to the default system
locations (`/usr/bin/ar` and `/usr/bin/ranlib`) when the `APPLE`
variable is set.
This commit removes application library CLI/NCP dependency on platform
layer UART APIs. Instead, application layer provides callbacks sending
CLI/NCP data.
With this change, platforms with native support for formatted output
can simply implement the CLI output callback with something like
`vprintf()`.
Abtin Keshavarzian