Fix that sign-in popup is unreliable (eg. blocked by default on Safari)

[Venryx]

No description provided.

[Venryx]

Made the change below just now (not yet pushed to GH), in attempt to fix this issue (not yet tested on Safari):

• MS sign-in panel retrieves the auth-link at time of panel open, rather than time of sign-in-button click. By doing this, the sign-in button can launch the sign-in popup immediately, rather than after a slight delay. (in attempt to fix popup-blocked issue on safari)

[Venryx]

After making the attempted fix (in previous comment), M-A did a quick test on a Safari browser, and did not hit the issue. (granted, the issue was unreliable there)

So for now, presuming fixed.