[Cleanup] Add missing #include. Remove useless ones. IWYU part 2.

This is a follow-up to
https://webrtc-review.googlesource.com/c/src/+/106280.
This time the whole code base is covered.
Some files may have not been fixed though, whenever the IWYU tool
was breaking the build.

Bug: webrtc:8311
Change-Id: I2c31f552a87e887d33931d46e87b6208b1e483ef
Reviewed-on: https://webrtc-review.googlesource.com/c/111965
Commit-Queue: Yves Gerey <yvesg@google.com>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25830}
diff --git a/rtc_base/httpcommon.cc b/rtc_base/httpcommon.cc
index 4fa5f41..13d0c1a 100644
--- a/rtc_base/httpcommon.cc
+++ b/rtc_base/httpcommon.cc
@@ -14,25 +14,24 @@
 #include <windows.h>
 #include <winsock2.h>
 #include <ws2tcpip.h>
+
 #define SECURITY_WIN32
 #include <security.h>
 #endif
 
 #include <ctype.h>  // for isspace
 #include <stdio.h>  // for sprintf
-#include <algorithm>
 #include <utility>  // for pair
 #include <vector>
 
 #include "absl/strings/match.h"
-#include "rtc_base/arraysize.h"
-#include "rtc_base/checks.h"
 #include "rtc_base/cryptstring.h"  // for CryptString
 #include "rtc_base/httpcommon.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/messagedigest.h"
 #include "rtc_base/socketaddress.h"
 #include "rtc_base/strings/string_builder.h"
+#include "rtc_base/stringutils.h"
 #include "rtc_base/third_party/base64/base64.h"  // for Base64
 #include "rtc_base/zero_memory.h"                // for ExplicitZeroMemory