x/tools/gopls: register semantic tokens with textDocument/semanticTokens

[stamblerre]

We currently use textDocument/semanticTokens/full only, but the correct way is textDocument/semanticTokens. We'll have to register semantic tokens both ways to avoid regressing, but we'll eventually be able to remove the multiple registration capabilities after the next VS Code Go release.

This will depend on the release of the next version of the vscode-languageclient. See microsoft/language-server-protocol#1107 for context.

[gopherbot]

Change https://golang.org/cl/266497 mentions this issue: package.json: upgrade to the latest vscode-languageclient pre-release

[gopherbot]

Change https://golang.org/cl/266479 mentions this issue: internal/lsp: use the correct method name to register semantic tokens

[stamblerre]

Leaving this open after https://golang.org/cl/266479 to track the deletion of the semanticTokenRegistrations function.

[gopherbot]

Change https://golang.org/cl/270359 mentions this issue: internal/lsp: fix capability registration for semantic tokens