My Jetpack: Allow redirect to arbitrary page after Jetpack connection

The ConnectionScreen component allows the use of a `returnTo` parameter to redirect the user after connection:
https://github.com/Automattic/jetpack/blob/7d9b325e165616e2d7ef0ed6aa7dbd6b2e6610cd/projects/packages/my-jetpack/_inc/components/connection-screen/index.jsx#LL49C2-L49C50

But that is hardcoded to only allow pages within My Jetpack: https://github.com/Automattic/jetpack/blob/7d9b325e165616e2d7ef0ed6aa7dbd6b2e6610cd/projects/packages/my-jetpack/_inc/components/connection-screen/index.jsx#L117

When establishing a connection from a prompt in the block editor, the user might expect to be redirected back to the block editor, which is not possible with this limitation.

ref p1685127123551239/1685125754.087739-slack-C054LN8RNVA

Start in projects/packages/my-jetpack/_inc/components/connection-screen/index.jsx, reading the returnTo parameter and the restriction around line 117. Check how connection is initiated from the block editor, then update the behavior so the post-connection redirect can return there or another requested page; done means the redirect is no longer limited to My Jetpack pages.

Written by the indexing model from the issue text.