WebShareDialog: add transaction-done signal
WebShareDialog: add transaction-done signal

Add signal to know when the we got redirected to redirect-uri
which means the web transaction ended.

https://phabricator.endlessm.com/T18524

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib