Fix std::tmpnam deprecation in event_log_visualizer

This CL replaces the deprecated std::tmpnam() function with
webrtc::test::TempFilename() to avoid compiler warnings on macOS.

This change requires:
1. Marking rtc_executable("event_log_visualizer") as testonly = true.
2. Adding dependencies on //test:test_support and //test:fileutils.
3. Removing the -Wno-deprecated-declarations suppression flag.

Bug: webrtc:14248
Change-Id: I8989a1839fabf70549843fd37d1c35df6c470efd
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/448160
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#46883}