[backport#15450 3/5] Add CreateWalletDialog to create wallets from the GUI

Summary:
Co-authored-by: João Barbosa <joao.paulo.barbosa@gmail.com>

https://github.com/bitcoin/bitcoin/pull/15450/commits/78863e290006e61060622dbdbecc5b58c0fefa05

Depends on D7103

Partial backport of Core PR15450

Test Plan:

ninja check

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D7104