Kernel+SystemServer+CrashDaemon: Better control where we put core dumps

SystemServer now creates the /tmp/coredump and /tmp/profiler_coredumps
directories at startup, ensuring that they are owned by root, and with
basic 0755 permissions.

The kernel will also now refuse to put core dumps in a directory that
doesn't fulfill the following criteria:

- Owned by 0:0
- Directory with sticky bit not set
- 0755 permissions

Fixes #4435
Fixes #4850

Services/CrashDaemon/main.cpp

@@ -74,9 +74,7 @@ static void launch_crash_reporter(const String& coredump_path)
 
 int main()
 {
-    static constexpr const char* coredumps_dir = "/tmp/coredump";
-    mkdir(coredumps_dir, 0777);
-    Core::DirectoryWatcher watcher { coredumps_dir };
+    Core::DirectoryWatcher watcher { "/tmp/coredump" };
     while (true) {
         auto event = watcher.wait_for_event();
         ASSERT(event.has_value());