* fix: only try SafeApp connection in an iframe
Improves non-iframe pageload by 300ms. Fixes#2338.
The Gnosis check for a SafeApp races a postMessage and a 300ms timeout [1]. The SafeApp embeds the interface in an iframe, so this avoids the check when not in iframes.
[1]: f224869dd5/packages/safe-apps-web3-react/src/connector.ts (L52)
* refactor: IS_IN_IFRAME const
* feat: support connecting to a gnosis safe
* add the manifest.json attributes required by gnosis safe
* remove background fill
* copy
* only try injected provider if not active after trying safe