cmake: fix setup_compiler by wrapping Compiler.cmake in a function

CMakeLists.txt calls setup_compiler(TARGET) after including
cmake/Compiler.cmake, but Compiler.cmake only contained flat cmake
code using ${PROJECT_NAME} directly — the setup_compiler function
was never defined, causing:

  CMake Error: Unknown CMake command "setup_compiler"

Fix: wrap the content of cmake/Compiler.cmake in
function(setup_compiler TARGET) and replace ${PROJECT_NAME}
references with ${TARGET} so the include/call pattern works
correctly.

Author: blshkv

cmake/Compiler.cmake

@@ -1,12 +1,13 @@
-set_target_properties(${PROJECT_NAME}
+function(setup_compiler TARGET)
+set_target_properties(${TARGET}
     PROPERTIES
         EXPORT_COMPILE_COMMANDS ON
         CXX_STANDARD_REQUIRED YES
         CXX_EXTENSIONS NO
         CXX_STANDARD 17
 )
 
-target_compile_features(${PROJECT_NAME}
+target_compile_features(${TARGET}
     PRIVATE
         cxx_std_17
 )
@@ -54,14 +55,15 @@ if(CMAKE_BUILD_TYPE STREQUAL "Debug")
     )
 endif()
 
-target_compile_options(${PROJECT_NAME}
+target_compile_options(${TARGET}
     PRIVATE
         $<$<CXX_COMPILER_ID:MSVC>:${MSVC_COMPILE_OPTIONS}>
         $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:${NOT_MSVC_COMPILE_OPTIONS}>
 )
 
-target_link_options(${PROJECT_NAME}
+target_link_options(${TARGET}
     PUBLIC
         $<$<CXX_COMPILER_ID:MSVC>:${MSVC_LINK_OPTIONS}>
         $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:${NOT_MSVC_LINK_OPTIONS}>
 )
+endfunction()