Support new useFcmV1 query param

[carl0shd]

Hi Guys, FCM legacy is deprecated and will be unusable after June 20, 2024. The idea is to support the new query param called useFcmV1

[RRaideRR]

@carl0shd Done and merged into master :)

• Added optional parameter force_fcm_v1 for PushClient initialization. If True, it will send Android notifications via FCM V1.