Fix JWT Claims and Socket Flag Handling to Improve Just Dance® Server Connection

I've changed the following:

Fix JWT token generation

• Updated the Subject in SecurityTokenDescriptor to use ClaimsIdentity so the claim is properly embedded in the token.
• Fixed random number generation for deviceAccountId.

Update socket flag handling in IClient.cs

• Refined logic for F_SETFL by setting socket.Blocking based on arg, aligning behavior with FreeBSD's implementation.
• This resolves the EOPNOTSUPP error encountered when running Just Dance®.

Outcome These changes allow Just Dance® to progress further in connecting to the server. However, after a successful connection, the following warning is now logged every microsecond:)

|W| HLE.GuestThread.46 KernelSvc : WaitSynchronization(handleIndex: 0x00000000) = InvalidHandle

Further investigation is needed to address this new issue.