This way we can take into account UDS_DISPLAY_NAME for locations like desktop:/, trash:/, etc

With this patch and D5221 I now (still) get "Desktop Folder" as heading but it's now deduced from what the KIO provides rather than being hardcoded.

trash:/ is also "Trash" now, and my places:/ KIO of D4979 shows up as "Places" now.

closestItem handling for places still works, e.h. /home/foo/Pictures is "Pictures" and also "breadcrumbs" like "Pictures > Foo > Bar" still works.

While at it I changed toString to toDisplayString which strips passwords from the URLs (should probably do an additional 5.8 patch for that)

Tilde expansion was removed as the code already only operated on the resolvedUrl from the dir model, resolving the tilde happens elsewhere and still works (custom location ~/Pictures still works)