Add timestamp, block ID, and (maybe?) confirmations to the Transaction data type

[telestrial]

Feel free to amend as necessary. We're currently missing these from the sibling Sia Central transaction-type request.

[telestrial]

@chris124567 @n8maninger I know there was some work done here fixing/modifying the pull that closed this issue. I believe this is settled now? One can now fetch the chain index of a transaction via the new route. That directly gets you the blockID. From there:

1. Is the confirmations the difference between the height in the chain index and the current height? Is this guaranteed to always be true?
2. How does one get the timestamp?

[n8maninger]

Timestamp is the block timestamp
Confirmations is the difference in heights