Kernel+Userland: Expose list of network adapters through /proc/netadapters.

Added a simple /bin/ifconfig program that just pretty-prints that file. :^)

Userland/ifconfig.cpp

@@ -0,0 +1,30 @@
+#include <LibCore/CFile.h>
+#include <stdio.h>
+
+int main(int argc, char** argv)
+{
+    UNUSED_PARAM(argc);
+    UNUSED_PARAM(argv);
+
+    CFile file("/proc/netadapters");
+    if (!file.open(CIODevice::ReadOnly)) {
+        fprintf(stderr, "Error: %s\n", file.error_string());
+        return 1;
+    }
+
+    for (;;) {
+        auto line = file.read_line(1024);
+        if (line.is_null())
+            break;
+        auto parts = String::copy(line, Chomp).split(',');
+        if (parts.size() < 4)
+            continue;
+        printf("%s:\n", parts[0].characters());
+        printf("     mac: %s\n", parts[2].characters());
+        printf("    ipv4: %s\n", parts[3].characters());
+        printf("   class: %s\n", parts[1].characters());
+        printf("\n");
+    }
+
+    return 0;
+}