ps: Port to using CProcessStatisticsReader and /proc/all

Drop /proc/summary in the process.
We only needed one new field here, thankfully, so this was quite straightforward.

Userland/ps.cpp

@@ -1,4 +1,5 @@
 #include <LibCore/CFile.h>
+#include <LibCore/CProcessStatisticsReader.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -8,13 +9,30 @@ int main(int argc, char** argv)
     (void)argc;
     (void)argv;
 
-    CFile f("/proc/summary");
-    if (!f.open(CIODevice::ReadOnly)) {
-        fprintf(stderr, "open: failed to open /proc/summary: %s", f.error_string());
-        return 1;
+    printf("PID TPG PGP SID  OWNER  STATE      PPID NSCHED     FDS  TTY  NAME\n");
+
+    auto all_processes = CProcessStatisticsReader::get_all();
+
+    for (const auto& it : all_processes) {
+        const auto& proc = it.value;
+        auto tty = proc.tty;
+
+        if (tty != "notty")
+            tty = strrchr(tty.characters(), '/') + 1;
+
+        printf("%-3u %-3u %-3u %-3u  %-4u   %-8s   %-3u  %-9u  %-3u  %-4s  %s\n",
+            proc.pid,
+            proc.pgid,
+            proc.pgp,
+            proc.sid,
+            proc.uid,
+            proc.state.characters(),
+            proc.ppid,
+            proc.times_scheduled,
+            proc.nfds,
+            tty.characters(),
+            proc.name.characters());
     }
-    const auto& b = f.read_all();
-    for (auto i = 0; i < b.size(); ++i)
-        putchar(b[i]);
+
     return 0;
 }