Support custom timeouts for txn confirmation

[dizpers]

Summary

This PR is based on the changes made in #2. The whole idea is to add configurable timeout for both transaction submission and confirmation.

Changes

• Separate configurable timeout for txn submission and txn confirmation
• A way to specify timeout in order placement (and other functions)
• Default values for txn submission timeout and txn confirmation timeouts
• Custom exception for txn submission failure and txn confirmation failure

Context

Some of the operations (e.g. orders cancellation) is taking more than default 30 seconds to confirm the transaction. So the custom software (e.g. Hummingbot connector) needs a way to explicitly set the timeout for those operations, set a bigger value.

E.g. order cancellation on testnet is taking up to 90 seconds, while default timeout was just 30 seconds. So it's possible that we (1) send a txn and it succeeds in 90 seconds (2) but timeout is 30 seconds (3) a trading bot see timeout error and retry cancellation for an order which is already cancelled.

Custom exceptions are needed for the client software can understand if a txn was submitted or not. To perform re-try logic.

Usage Example

    # Use default timeouts (10s submit, 30s confirm)
    await dex.place_order(...)
    await dex.cancel_order(...)

    # Use custom confirmation timeout for slow networks
    await dex.place_order(..., txn_confirm_timeout=60.0)
    await dex.cancel_order(..., txn_confirm_timeout=90.0)

    # Sync usage
    dex_sync.place_order(..., txn_confirm_timeout=45.0)

Testing

Tested on testnet and mainnet