internal/lsp: use ranges instead of positions in completion items
internal/lsp: use ranges instead of positions in completion items

Fixes golang/go#32078

Change-Id: If33cc6f7a914e6ef17d06a34c39dceb61cfa16d4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/177657
Run-TryBot: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>
Reviewed-by: Ian Cottrell <52376736e5e84615ec49f9c1843b8acc178b1d8d@google.com>

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