Hides the spinner when user clicks on other tabs.
When Install From Web is too slow, this allows not to wait and to be able to upload the extension from local disk, for instance.
@tushevorg The only thing is that the plugin itself has to behave correctly, so trying to patch com_installer for the bad behavior of web installer feels kinda weird. My 2c!
There is another solution applied to the web installer itself: joomla-extensions/install-from-web-client#23
It also needs some tests...