internal/lsp: build the wire.Node lazily
internal/lsp: build the wire.Node lazily

this is needed to move to a model where we do not need to have
the wire form at all

Change-Id: I3b3693e027b568de4e8b4d10f7d5dd022a616e2e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/208958
Run-TryBot: Ian Cottrell <52376736e5e84615ec49f9c1843b8acc178b1d8d@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Emmanuel Odeke <277f8eaa8c7dfbc55c17bf5e30561c1a9c45c569@gmail.com>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools