Add possibility to use async requests on choose password

[vince1995]

Is your feature request related to a problem? Please describe.
Because JavaScript must be available in choose_password the form which redirects to another page seems needless.

Describe the solution you'd like
To uphold backwards compatibility add a simple flag shouldNotRedirect to the body of the POST request and just respond with the status code 200 instead of 302.

Describe alternatives you've considered
I'm using a custom page and proxying the request to keep a SPA instead of getting an unneeded redirect (which causes a full refresh of my website).

[dplewis]

@vince1995 A PR #5332 was submitted. Would something like this help?

[vince1995]

Oh wow, yeah, that's exactly what I imagined. Sorry, searched in issues for that feature but not in PRs. You can close.