@ContentChild[ren] and @ViewChild[ren] can contain a forwardRef() to a
type. This commit allows ngtsc to unwrap the forward reference and
deal with the node inside.
It includes two modes of support for forward reference resolution -
a foreign function resolver which understands deeply nested forward
references in expressions that are being statically evaluated, and
an unwrapForwardRef() function which deals only with top-level nodes.
Both will be useful in the future, but for now only unwrapForwardRef()
is used.
PR Close#25080