Add File.executable? for Windows (#9677)

Co-authored-by: Johannes Müller <straightshoota@gmail.com>

spec/std/file_spec.cr

@@ -132,17 +132,16 @@ describe "File" do
     end
   end
 
-  # TODO: implement this for win32
   describe "executable?" do
-    pending_win32 "gives false" do
+    it "gives false" do
       File.executable?(datapath("test_file.txt")).should be_false
     end
 
-    pending_win32 "gives false when the file doesn't exist" do
+    it "gives false when the file doesn't exist" do
       File.executable?(datapath("non_existing_file.txt")).should be_false
     end
 
-    pending_win32 "gives false when a component of the path is a file" do
+    it "gives false when a component of the path is a file" do
       File.executable?(datapath("dir", "test_file.txt", "")).should be_false
     end
   end

src/crystal/system/win32/file.cr

@@ -124,7 +124,7 @@ module Crystal::System::File
   end
 
   def self.executable?(path) : Bool
-    raise NotImplementedError.new("File.executable?")
+    LibC.GetBinaryTypeW(to_windows_path(path), out result) != 0
   end
 
   private def self.accessible?(path, mode)

src/lib_c/x86_64-windows-msvc/c/winbase.cr

@@ -41,4 +41,6 @@ lib LibC
   MOVEFILE_FAIL_IF_NOT_TRACKABLE = 0x20_u32
 
   fun MoveFileExW(lpExistingFileName : LPWSTR, lpNewFileName : LPWSTR, dwFlags : DWORD) : BOOL
+
+  fun GetBinaryTypeW(lpApplicationName : LPWSTR, lpBinaryType : DWORD*) : BOOL
 end