Selectable keystore path

[Atralupus]

Users who play games on multiple devices or care about security, will want to play with a private key in USB.
Especially if they bought a lot of NCG, they will use USB more
I hope the option is added so that the launcher can modify the keystore path
I tried to fix on the v2 launcher, but the UI didn't come out pretty because the settings window was a little narrow.
If you proceed, you may need to add a scroll to the settings window.
I'd be so so so happy if there were additional functions😆

[BasixKOR]

This feature requires the headless and game to allow customized keystore path, thus blocked by upstream.

[dahlia]

AFAIK the headless currently uses Web3KeyStore.DefaultKeyStore which sees the system default path ($HOME/.config/planetarium/keystore or %AppData%\planetarium\keystore). In order to specify a different key store path, the headless need to instantiate its own Web3KeyStore object using the constructor.