The Go extension will require go1.21 for tools installation from v0.44.0
(and is prerelease version v0.43.x).

This is a planned change and it was discussed in the v0.42.0 release note.
(https://github.com/golang/vscode-go/releases/tag/v0.42.0 Jul 17 2024).

`installTools` is the entry function for tools installation.
If the go version is too old, it suggests go1.21+ or the workaround
(go.toolsManagement.go).

* Misc changes
 - Previously, when the build info of a binary is not available,
   we didn't ask to update the tool. Since go1.18, the build info
   should be available. So, now suggest to reinstall the tool.
 - Bug fix: For vscgo, we used toolExecutionEnvironment when running
   go install.
   It should be toolInstallationEnvironment. This clears some env vars
   like GO111MODULE, GOPROXY, GOOS, GOARCH, GOROOT which can interfere
   with the go tool invocation.

Fixes #3411

Change-Id: Ifff0661d88a9adfc6bd3e0a25702d91921bcb77f

We want to use the latest go when developing our own
release/testing support tools and scripts.
So, update go.mod to do so.

However, we need to be careful when using
the `installtools` script.
The purpose of `installtools` is to install tools
needed by integration tests. It selected the latest
version of each tool compatible with the default
go version in the system. For example, in the CI is
setup with go1.22, we want to install tools that
officially claim they support go1.22.

`installtools` detects the go version using
the `go` command. As we change our go.mod to use
go1.23.1 as the go directive, the `go` command running
under our project's repo directory (with GOTOOLCHAIN=auto)
will always be go1.23.1 or newer. That makes go1.22 CI
meaningless.

So, pass `GOTOOLCHAIN=local` when `installtools` computes
the go version using `go list`.

Previously we used `go run` to build/invoke this tool.
But it turned out `go run`/`go generate` modify
(or will modify) `GOROOT` and/or `PATH` when toolchain
switch occurs, which will prevent `installtools`
from detecting the system default toolchain version
even with `GOTOOLCHAIN=local`, or cause the
build fail due to mismatching GOROOT and go toolchain
picked up from PATH.

Therefore, in this CL, we build the binary (it's ok to
build the binary with go1.23.1+), and then run
the installed binary ourselves so the execution of
the binary doesn't get inherit the modified GOROOT/PATH.

For #3411

Change-Id: I3e116cf48fb431196359ec42049e70c0b75814ef

The types are moved to tools/gopls/internal/doc/api.go.

Remove `JSON` suffix from each name.

Change-Id: Ic5dae90f83f32f241a1e128aecd7def92aff34bc

gopls v0.17 will have LinksInHover that is the true|false|"gopls"
enum type. Previously, we assumed enum type is always string. That
is no longer true. Handle this sum-type enum.

For golang/go#68057

Change-Id: I9eb2e8376191d997895f8998bfffb2662fbfb92e

latestPrereleaseVersion and latestPrereleaseVersionTimestamp
fields are not read.

Usually, the prerelease version lasts short and it becomes
obsolete by the stable version, so this info often gets
outdated anyway.

Change-Id: If0513e3a95426dc1ff1803542aa981d7aed00593

FORCE RUN CI

This field was added when we were deprecating several tools with gopls
gradually and we wanted to keep the complexity of `getConfiguredTools`
manageable. Now we have only a handful number of tools. Remove it.

Also, remove the custom formatter check in getConfiguredTools.
The idea was to add a custom formatter tool to the configured tools list
if the user configured "go.formatTool": "custom". But, since custom tool
name won't be in `allToolsInformation`, so the custom tool won't be
included in the list anyway. (We install only tools known to us).

Change-Id: I4b26d3756fe45e1cc29f8434b1b5d83ee8977d47

This suppresses the "Failed to connect to the bus" error.

Change-Id: Ie193b92085906121ba337bcf4a3af4428c87b31e

FORCE RUN CI

This script runs in CI with the go version under testing.
Prevent the go toolchain switch from getting influenced by
extension/go.mod's choice of go version.

Add a go.mod file with go1.12 to testdata/envTest
to prevent go toolchain switch to go1.23 (which will fail
due to GOTOOLCHAIN=local).

Change-Id: I02f1cd6512a0030a729668221b163f6cc3e26b0f

FORCE RUN CI

Change-Id: If436bb675dd5e5e8a5782621f273c5c16247493d