build: build ffmpeg and native_mksnapshot for GN release builds (#14240)

* build ffmpeg and native_mksnapshot for GN release builds

* Test ffmpeg via verify-ffmpeg.py

* remove sccache from Windows builds

build/args/testing.gn

@@ -1,6 +1,7 @@
 import("all.gn")
 is_debug = false
 is_component_build = false
+is_component_ffmpeg = true
 is_official_build = false
 dcheck_always_on = true
 symbol_level = 1