Add 'rtc_p2p_unittests' missing dependencies.

This is a follow up of https://webrtc-review.googlesource.com/c/src/+/362480.

Change-Id: Idba0153f3770a3de50d82b2dac62b345e3e2c9c8
Bug: None
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/374480
Auto-Submit: Jeremy Leconte <jleconte@webrtc.org>
Reviewed-by: Christoffer Dewerin <jansson@webrtc.org>
Commit-Queue: Christoffer Dewerin <jansson@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43747}

p2p/BUILD.gn

@@ -1279,7 +1279,9 @@ if (rtc_include_tests) {
       "../test:test_support",
       "//testing/gtest",
       "//third_party/abseil-cpp/absl/algorithm:container",
+      "//third_party/abseil-cpp/absl/functional:any_invocable",
       "//third_party/abseil-cpp/absl/memory",
+      "//third_party/abseil-cpp/absl/strings",
       "//third_party/abseil-cpp/absl/strings:string_view",
     ]
   }