Fixes #763
Preventing users from creating a legacy wallet prior to its deprecation in the upcoming releases.
Note:
This is still available using the createwallet RPC command.
Future Note: Would be nice to re-write this modal as a wizard. And improve the design.
<details><summary> Pre-Changes Screenshot </summary> <img width="611" alt="Screenshot 2023-10-06 at 11 30 14" src="https://github.com/bitcoin-core/gui/assets/5377650/ca10c97d-46e8-4aed-82da-068f2afbe25c"> </details>
<details><summary> Post-Changes Screenshot </summary> <img width="729" alt="Screenshot 2023-10-06 at 11 32 58" src="https://github.com/bitcoin-core/gui/assets/5377650/f6bdcb57-646a-43d8-86a7-476e3cca683f"> </details>