[cmake] update CMake configurations for Apple platforms (#12729)

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.

examples/apps/cli/ftd.cmake

@@ -56,7 +56,7 @@ target_link_libraries(ot-cli-ftd PRIVATE
 )
 
 if(OT_LINKER_MAP)
-    if("${CMAKE_CXX_COMPILER_ID}" MATCHES "AppleClang")
+    if(APPLE)
         target_link_libraries(ot-cli-ftd PRIVATE -Wl,-map,ot-cli-ftd.map)
     else()
         target_link_libraries(ot-cli-ftd PRIVATE -Wl,-Map=ot-cli-ftd.map)

examples/apps/cli/mtd.cmake

@@ -56,7 +56,7 @@ target_link_libraries(ot-cli-mtd PRIVATE
 )
 
 if(OT_LINKER_MAP)
-    if("${CMAKE_CXX_COMPILER_ID}" MATCHES "AppleClang")
+    if(APPLE)
         target_link_libraries(ot-cli-mtd PRIVATE -Wl,-map,ot-cli-mtd.map)
     else()
         target_link_libraries(ot-cli-mtd PRIVATE -Wl,-Map=ot-cli-mtd.map)

examples/apps/cli/radio.cmake

@@ -60,7 +60,7 @@ target_link_libraries(ot-cli-radio PRIVATE
 )
 
 if(OT_LINKER_MAP)
-    if("${CMAKE_CXX_COMPILER_ID}" MATCHES "AppleClang")
+    if(APPLE)
         target_link_libraries(ot-cli-radio PRIVATE -Wl,-map,ot-cli-radio.map)
     else()
         target_link_libraries(ot-cli-radio PRIVATE -Wl,-Map=ot-cli-radio.map)