b3b6b6f62f gui: don't disable the sync overlay when wallet is disabled (Ben Carman)
Pull request description:
Continuation of #13848.
When running with `-disablewallet` the sync modal is now available by clicking on the progress bar or `syncing` icon.
[Current Image of what the window looks like](https://imgur.com/6LsoT2l)
Fixes#13828.
ACKs for top commit:
jonasschnelli:
Tested ACK b3b6b6f62f
Tree-SHA512: 325bc22a0b692bfb8fcc9d84e02dfc506146028b97b3609e23c2c45288c79b8aead1ad2e9b8d692f5f6771b4d2aee63fbe71bfaeaf17d260865da32ab3631e07