Store: Fix race condition causing crashes if looking at another game before an icon finishes downloading #7903

Job	Run time
build-uwp	12m 19s
build-windows (x64)	15m 52s
build-windows (ARM64)	14m 53s
build (ubuntu-latest, test, clang, clang++, ./b.sh --headless --unittest, clang-normal)	4m 47s
build (ubuntu-latest, gcc, g++, ./b.sh --headless --unittest, gcc-normal)	3m 31s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=arm64-v8a UNITTE...	12m 23s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=armeabi-v7a UNIT...	7m 17s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=x86_64 UNITTEST=...	11m 40s
build (ubuntu-latest, android, clang, clang++, cd android && ./ab.sh -j2 APP_ABI=arm64-v8a OPENXR...	9m 40s
build (ubuntu-latest, android, clang, clang++, ./b.sh --libretro_android ppsspp_libretro, android...	4m 31s
build (ubuntu-latest, qt, gcc, g++, ./b.sh --qt, qt)	4m 6s
build (ubuntu-latest, libretro, gcc, g++, make -C libretro -f Makefile -j2, gcc-libretro)	3m 42s
build (ubuntu-latest, libretro, clang, clang++, make -C libretro -f Makefile -j2, clang-libretro)	2m 50s
build (macos-latest, test, clang, clang++, ./b.sh --headless --unittest --fat --no-png --no-sdl2,...	28m 51s
build (macos-latest, ios, clang, clang++, ./b.sh --ios, ios)	6m 18s
test-windows	1m 28s
test (ubuntu-latest)	1m 17s
test (macos-latest)	43s
	2h 26m 8s

Provide feedback