Fix native implementation

src/macosMain/kotlin/com/infendro/shell/Shell.macos.kt

@@ -0,0 +1,20 @@
+package com.infendro.shell
+
+import platform.posix.chdir
+import platform.posix.pclose
+import platform.posix.popen
+import kotlin.coroutines.resume
+import kotlin.coroutines.suspendCoroutine
+
+actual suspend fun execute(vararg command: String, directory: String?): Result = suspendCoroutine { continuation ->
+    val command = command.joinToString(" ") { """"$it"""" }
+    if (directory != null) {
+        chdir(directory)
+    }
+    val stream = popen(command, "r")!!
+    val value = stream.readLines().joinToString("")
+    val code = pclose(stream)
+
+    val result = Result.from(code, value)
+    continuation.resume(result)
+}