x/tools/gopls: make jsonrpc2, lsp, span and friends non-internal

[myitcv]

Per discussion on Slack, adding a placeholder to track making the following packages non-internal once they stabilise:

golang.org/x/tools/internal/jsonrpc2
golang.org/x/tools/internal/lsp/...
golang.org/x/tools/internal/span

The use case being, people writing LSP clients in Go can then readily leverage these packages.

cc @stamblerre @ianthehat

[gopherbot]

Change https://golang.org/cl/170920 mentions this issue: tools/lsp: moved span, lsp/protocol and lsp/jsonrpc2 out of internal

[gmwxio]

Per discussion on Slack, adding a placeholder to track making the following packages non-internal once they stabilise:

How do I find the Slack channel?

[myitcv]

@wxio - you don't have to join the Slack channel to participate in discussions about the LSP, I was simply noting that I had had a conversation with @ianthehat there.

More details on the various channels used for tools discussion:

https://github.com/golang/go/wiki/golang-tools

[gmwxio]

@myitcv join the slack group. Is the LSP discussion on a specific channel?

[myitcv]

Per https://github.com/golang/go/wiki/golang-tools, most of the chat happens in #tools

[fhs]

internal/lsp/protocol API seems to be too strict at the moment and only designed to work with gopls. For example, ServerCapabilities.renameProvider can be either bool or RenameOptions, but the protocol package expects RenameOptions. This breaks compatibility with go-langserver, which sends a bool. The current protocol package is not going to be very useful to me because I want to write a lsp client that supports all LSP servers that follow the LSP protocol.