[KleinanzeigenBridge] random improvements and fixes (#4821)* [KleinanzeigenBridge] random improvements and fixesPrevious MR #4820 introduced a bug where the URI wasn't gettingexpanded. This is because it is obtained from a non-standard data-uriattribute which defaultLinkTo() doesn't support.On top of that:- sanitizes the HTML in Content- use a longer Description found in JSON- fix timestamp processing, including for relative Today and Yesterday strings- move media to enclousures- be explicit about elements chosen to augument the description- simplify the image URL processing* [KleinanzeigenBridge]: add Buy It Now filter