Show fee in decoded and unconfirmed txs

[matheusd]

trafficstars

It would be nice to see the fee and fee rate of decoded (eg: prior to manually broadcasting a tx) and unconfirmed transactions.

Though to get the decoded fee you'd have to look at the utxos, so it might be tricky to do on the current flow of the decoding call.

[raedah]

This is a variation of https://github.com/decred/dcrdata/issues/130 and https://github.com/decred/dcrdata/issues/142

[ukane-philemon]

@chappjc, is this still an issue?

[chappjc]

We clearly show it for all transactions on the transaction page, but we could add it to the json response (what he means by "decoded").