Grant virtualization - Phase 2

[NejcZdovc]

Follow up of #6078

Completed

• add check for public key (public keys from initial promotion fetch should be checked against public key that is send with signed tokens) Check public key #6939 -> Adds check for public key when getting tokens brave-core#4008
• if unblinded token expires we need to remove it Check if token expired before using it #7022 -> Token check brave-core#4025
• handle promotion expiration (and unblinded tokens with it) Promotion expiration #6947 -> Promotion expiration brave-core#4035
• add migration flow for old grants Add migration flow for old grants to new promotions #6937 -> Add migration flow for old grants to new promotions brave-core#4101
• add retry logic for contribution Retry logic for unblided tokens contribution #6940 -> Adds delays for suggestion api brave-core#4372
• implement new claim api for uphold where we send unblinded tokens to the server and then transfer it to uphold Add claim option for VG #8354 -> Adds claim api for vg brave-core#4708

In progress

• add unit tests Unit tests for virtual grants #6949 -> Unit tests for virtual grants brave-core#4344

Backlog

• do not delete tokens Do not delete unblinded tokens #8181

Blocked

• backup and restore of unblinded tokens Backup/Restore for unblinded tokens #6938 (waiting on server to implement new flow)
• when doing AC with uphold we should have API that convert BAT to blinded tokens AC with virtual grants flow with uphold funds #7595
• remove anonize and old contribution code Remove anonize #7717
• implement new create persona api Implement new persona creation #8428
• implement wallet create attestation platform agnostic Wallet create attestation platform agnostic #6945 (need to define flow)

[NejcZdovc]

all was done