x/tools/gopls: gc_details codelens is broken because gopls_gc_details command is not included in initialization

[hyangah]

$ gopls -v version
Build info
----------
golang.org/x/tools/gopls master
    golang.org/x/tools/gopls@v0.0.0-20201014170642-d1624618ad65 h1:lvYvyth3KR9zDdDRWZ6Olt3KNZ5iWVWLJPojDK1Kf0A=
    github.com/BurntSushi/toml@v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
    github.com/google/go-cmp@v0.5.1 h1:JFrFEBb2xKufg6XkJsJr+WbKb4FQlURi5RUcBveYu9k=
    github.com/sergi/go-diff@v1.1.0 h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=
    golang.org/x/mod@v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
    golang.org/x/sync@v0.0.0-20200625203802-6e8e738ad208 h1:qwRHBd0NqMbJxfbotnDhm2ByMI1Shq4Y6oRJo21SGJA=
    golang.org/x/tools@v0.0.0-20201014170642-d1624618ad65 h1:q80OtYaeeySe8Kqg0vjXehHwj5fUTqe3xOvnbi5w3Gg=
    golang.org/x/xerrors@v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
    honnef.co/go/tools@v0.0.1-2020.1.5 h1:nI5egYTGJakVyOryqLs1cQO5dO0ksin5XXs2pspk75k=
    mvdan.cc/gofumpt@v0.0.0-20200802201014-ab5a8192947d h1:t8TAw9WgTLghti7RYkpPmqk4JtQ3+wcP5GgZqgWeWLQ=
    mvdan.cc/xurls/v2@v2.2.0 h1:NSZPykBXJFCetGZykLAxaL6SIpvbVy/UFEniIfHAa8A=

$ gopls api-json | jq
{
    ...
    {
      "Command": "gc_details",
      "Title": "Toggle gc_details",
      "Doc": "gc_details controls calculation of gc annotations.\n"
    },
    ...
    {
      "Lens": "gc_details",
      "Title": "Toggle gc_details",
      "Doc": "gc_details controls calculation of gc annotations.\n"
    }
 }

Initialization still lists gc_details, so gc_details command is registered to vscode.

[Trace - 19:16:24.915 PM] Received response 'initialize - (0)' in 1ms.
Result: {
...
  "executeCommandProvider":{"commands":["generate","fill_struct","regenerate_cgo","test","tidy","undeclared_name","upgrade_dependency","vendor","extract_variable","extract_function","gc_details","generate_gopls_mod"]},
...
}

CodeLens uses gopls_gc_details

[Trace - 19:12:38.210 PM] Received response 'textDocument/codeLens - (21)' in 0ms.
Result: [{"range":{"start":{"line":0,"character":0},"end":{"line":0,"character":0}},"command":{"title":"Toggle gc annotation details","command":"gopls_gc_details","arguments":["file:///Users/hakim/hello/mypkg/mypkg.go"]}}]

Since gopls_gc_details was never registered, vscode just errors.
OTOH, vscode sends gc_details command to gopls, which results in 'no known command' error.

[gopherbot]

Change https://golang.org/cl/262354 mentions this issue: internal/lsp: send "gopls_" prefixed commands in initialize

[gopherbot]

Change https://golang.org/cl/262597 mentions this issue: internal/lsp/source: be consistent about command identifiers