kernel: add second example kext for dependency test

kexts/test-base/extension.yaml

@@ -0,0 +1,9 @@
+name: test-base
+description: |
+  A sample kernel extension, demonstrating the structure of a kext.
+  No actual functionality.
+id: net.doorstuck.socks.test-base
+license: BSD-3-Clause
+copyright: Copyright © Max Wash 2023
+sources:
+  - main.c

kexts/test-base/main.c

@@ -0,0 +1,12 @@
+#include <socks/printk.h>
+#include <socks/kext.h>
+
+static kern_status_t online(struct kext *self)
+{
+	printk("Kernel extension base online");
+	return KERN_OK;
+}
+
+DEFINE_KEXT("net.doorstuck.socks.test-base",
+	    online, NULL,
+	    KEXT_NO_DEPENDENCIES);