`BlazeAndroidSyncBuildFlagsProvider` should parse `fat_apk_cpu` flag from `build_flags` too

[kkpattern]

Currently, bazel intellij plugin will try to parse fat_apk_cpu flag from sync_flags. If no flag found x86_64 would be added to sync flags.

However, according to doc sync_flags should be used only when absolutely necessary, as it can defeat bazel caching. So normally we will add fat_apk_cpu in build_flags since it will also be added to sync flags.

But now if bazel intellij plugin doesn't find the fat_apk_cpu flag in sync_flags, it will add --fat_apk_cpu=x86_64 which further override the fat_apk_cpu in build_flags. This may cause sync to fail if the project doesn't target x86_64 platform.