Clear transactionHashes/error query string parameter after processing redirect from wallet

[petersalomonsen]

When the wallet redirects back to the widget after a transaction, it's possible to look up the transactionHashes parameter but no way to clear it ( or the other query string parameters returned from the wallet ) after processing it. This means that it will be re-processed if reloading the page, or even submitted to the wallet as the redirect url for following transactions.

It should be possible to clear query string parameters, or perform a redirect to another URL without user interaction.

More context can be found here: NEAR-DevHub/neardevhub-bos#217