Improve "sign for address" UX

[piyalbasu]

This has been raised a couple of times by users in the ecosystem:

Currently, in the sign tx/message/auth entry flow, we allow dapps to specify what address they're requesting a signature from by passing a param. If Freighter has that address, it automatically switches to that account to reduce friction and speed up the process. We do not currently switch the account back after the modal is open, regardless of whether the users completes signing or hits cancel.

2 possible improvements:

1. should we switch the account back to the original account after signing is complete? Or maybe only after a user cancels?

2. should we prompt the user to "opt-in" to switching the account for security purposes?

[JakeUrban]

It looks like other wallets within the industry have the same experience we have today -- switching to an account to sign a requested transaction results in that account being the selected account when you later open the wallet.