Update condition when creating a transaction: single vs batch

[germartinez]

Description

Update the condition inside createTransaction(...) that decides if the SDK will send a single or a batch transaction.
When passing an array of transaction as a parameter, take into account:

• If the length of the array is 0
• If the length of the array is 1 -> create single transaction

Check: https://gist.github.com/cmdzro/0547725ca6faa2067e7edf3c70b697f1#gistcomment-3954987