Fix: quotes appearing in content filter input
Created by: attfarhan
Fixes the issue in https://sourcegraph.slack.com/archives/C0W2E592M/p1583559994068500.
Now, in interactive mode, the content filter will always be quoted when the query is sent to the backend, but when we display the editable value to the user, it eliminates the quotes and escape sequences. This ensures URLs are always properly escaped.