LexemeView: return ViewContent
A view may return rendered HTML that still contains some placeholders.
This is not the case in lexeme but now taken into account inside the
interface by a complex type.
Bug: T206863
Depends-On: I3a61b5261a0076f116b07299b55508f706625076
Depends-On: Ic4f56c590cf870d17f2d199f2dd85115e9da5746
Change-Id: If864d1bbb8f7bcddb281e83298283dfc0b2f4f8f