Close the options window after clicking Save

[alanhamlett]

Currently there's no indication that the settings are saved after clicking Save button. We should close the options window after successfully saving the extension options, and for bonus show some kind of toast saying they were saved if possible.

[jvelezpo]

The toast will be part of the upgrade bootstrap to v5 PR

[PaoloJr90]

Hello! Just adding here that clicking Save in both the Chrome and Firefox browser extensions does not indicate that the Options were saved; it appears to be frozen (side-bar scroll indicator does show some movement). Perhaps I can work on this; will refer to the documenation on testing locally. Here is an image for reference: