services/send page - if the user doesn't have the token he is trying to send

[Anna15170221]

Currently, when a user tries to send a Token he does not hold, the transaction is submitted but fails with the error “Path dry.”
We need:

1. Pre-check before submission:

• Verify whether the sender holds the token they are attempting to send.
• If not, display an informative message before submitting the transaction.

2. Enable cross-currency payments:

• Allow users to send a token they don’t hold by using a cross-currency payment with auto-bridging.
• In such cases, the SendMax field must be specified in the Payment transaction.
  Example: A user doesn’t have the token but can still send it by paying with XRP.