Added Solana Actions support for transfer endpoint

[CodeMaverick2]

Added Solana Actions support for transfer endpoint

Solves Issue -> #16

Description:

This PR introduces support for Solana Actions by implementing a new transfer action handler. It reuses the existing transfer transaction logic to enable seamless token transfers between accounts.

Changes Implemented:

• Added actions.json entry for the transfer action.
• Created transfer.rs in crates/rpc/src/actions/ to handle transfer requests.
• Integrated with existing transfer transaction logic (transfer_transaction).
• Registered new RPC methods:
  • getTransferMetadata – Retrieves metadata for the transfer action.
  • transferAction – Processes transfer requests via JSON-RPC.
• Added unit tests (transfer_test.rs) to validate the new transfer flow.

Usage:

The transfer action can be invoked using the following Solana URL format:

solana://transfer?amount=1000000&token=So11111111111111111111111111111111111111112&source=<SOURCE_PUBKEY>&destination=<DESTINATION_PUBKEY>