extension/src/goInstallTools: strengthing minimum go version requirement

[koleskizzzzz]

This change addresses problems in tools installation surfaced by the recent changes in go and gopls.

• Automated toolchain switch for Go forwards compatibility

The automated Go toolchain switch change added in go1.21 changed the meaning of 'go version' output different. Previously, it was meant exactly the version of the toolchain on the system. After go1.21, this is a go version for chosen for the workspace, computed based on the local toolchain version and the required go version dictated by go.mod or go.work.

The extension has a facility to detect the go version used to compile tools, and ask users to rebuild them if they were built with older go standard libraries. When a local toolchain is older (for example, go1.21.0) than the workspace's required go version (go1.22.0), the 'go version' reports go1.22.0. The extension will detect tools that need recompiling to support go1.22.0 project. That works as expected.

However, when recompiling those tools with go install, the workspace's go version requirement doesn't come into play at all, but only the local toolchain's go version and the target tool's minimum required go version will be used in the toolchain switch decision making. As of today, none of the tools set their minimum required go version to go1.22.x, so if the local toolchain is still go1.21.0, go install will use go1.21.0 for build.

We need to explicitly specify the minimum required version using the GOTOOLCHAIN environment variable. In this example, go install with GOTOOLCHAIN=go1.22.0+auto will address the issue.

In this CL,

• extend getGoVersion to allow the local toolchain version by specifying the optional GOTOOLCHAIN parameter.
• change getGoForInstall to produce the correct GoVersion object that carries the true version of the local toolchain. (computed with getGoVersion(..., 'local')).
• change installTools to append the GOTOOLCHAIN env var if the go version to be used for install is older than the project's minimum required go version.

• More frequent crashes/malfunctions upon version mismatch

Gopls is supposed to prompt when it detects it needs to be recompiled to process the modules that require newer go versions. The extension has relied this as the second, and more reliable defense mechanism. Unfortunately, bugs in the recent gopls stopped gopls from reliably detecting this case or, even made the gopls crash before showing the notification.

Similar crashes can occur in other tools (#3168) when the version is mismatched. Previously, installTools warned users only if the go version for install was very old (e.g. go1.15).

In this CL,

• tighten installTools's installation tool version check further. So, if the project requires a newer version of go and the go configured for tools installation (maybe due to outdated 'go.toolsManagement.go' setting) is older and is a version that cannot handle automated version switch (<go1.21), it prompts users.

• Other changes

Testing involving two versions of go is complex. Changed the runTest helper for 'Installation Tests' test suite to accept extra parameters and stubs, so we can make the installation function under test believe the local go chosen for installation is an older version.

This CL also adjusted the logging of gopls restart activities. When gopls installed (automatically, or from the activation), the extension may attempt to restart the gopls. That may help investigate spurious gopls restarts obeserved during https://github.com/golang/vscode-go/issues/3307.

This CL stops clearing of the Go outputChannel before tool installation or goplay run. This channel is now a log output channel, so it's better not to clear.

Fixes #3168

Change-Id: Id9a4c0fe98c85efb17eb3351cfba5665a83b094d
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/577095
Reviewed-by: Peter Weinberger pjw@google.com
Commit-Queue: Hyang-Ah Hana Kim hyangah@gmail.com
Reviewed-by: Suzy Mueller suzmue@golang.org
kokoro-CI: kokoro noreply+kokoro@google.com

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