Use @sentry/react instead of @sentry/browser

[Vadorequest]

A new package from Sentry has recently been released. See getsentry/sentry-javascript#2631 in https://github.com/getsentry/sentry-javascript/releases/tag/5.18.0

It might be better to use this new lib instead, as it's meant to replace @sentry/browser.
I'm not aware of the implications of such a change, this would need to be POCed and thoroughly tested.

Asking for advices from Sentry before implementation/changes. See getsentry/sentry-javascript#3163

[Vadorequest]

Initial study: Bigger lib (+10kB), seem to handle more react stuff, not sure if it's meant to be universal or client only.

[Vadorequest]

Another package has been released specifically for Next.js. See #305

Closing this issue.