gui: Add transactionClicked and coinsSent signals to WalletView

Summary:

Two new signals are added beforehand in the first commit so that the connections in WalletFrame are all from the wallet view.

This is a backport of Core PR17937 [1/2]
https://github.com/bitcoin/bitcoin/pull/17937/commits/ac3d10777d65b68862c6deb57594c8fc4d21ca77

Test Plan:
ninja && src/qt/bitcoin-qt
Send a transaction, check that the transaction history page is automatically selected

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8698