Add cmake executor and default library path var wrapper

src/SPC/builder/unix/executor/Executor.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\unix\executor;
+
+use SPC\builder\freebsd\library\BSDLibraryBase;
+use SPC\builder\LibraryBase;
+use SPC\builder\linux\library\LinuxLibraryBase;
+use SPC\builder\macos\library\MacOSLibraryBase;
+
+abstract class Executor
+{
+    public function __construct(protected BSDLibraryBase|LinuxLibraryBase|MacOSLibraryBase $library) {}
+
+    public static function create(LibraryBase $library): static
+    {
+        return new static($library);
+    }
+
+    abstract public function build(): void;
+}