tools/internal/lsp/protocol: add LocationLink type
tools/internal/lsp/protocol: add LocationLink type

LocationLink was added in 3.14.0 of lsp.

Change-Id: I388dba5ab43b195cc3965e4199b49155094a2627
Reviewed-on: https://go-review.googlesource.com/c/156617
Reviewed-by: Ian Cottrell <52376736e5e84615ec49f9c1843b8acc178b1d8d@google.com>

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