[bun install] Implement bun link

src/cli/unlink_command.zig

@@ -0,0 +1,8 @@
+const Command = @import("../cli.zig").Command;
+const PackageManager = @import("../install/install.zig").PackageManager;
+
+pub const UnlinkCommand = struct {
+    pub fn exec(ctx: Command.Context) !void {
+        try PackageManager.unlink(ctx);
+    }
+};