Compile launcher Windows as a GUI binary to avoid cmd window prompts

[seejdev]

Fixed #943

This PR includes the change to enable Windows launcher to be built as a GUI binary instead of a console binary. We originally reverted this code but it appears this doesn't break autoupdate like we originally feared.

The second change updates the CI check to ignore any output and just verify that launcher --version ran successfully. This better matches the check that the autoupdate code performs on binaries.

Behavior changes

Windows CMD will wait for console binaries and return their output, whereas GUI binaries are not waited for and no output is returned:

launcher_console.exe --version
{"caller":"main.go:30","msg":"Launcher starting up","revision":"7e862bc58116421ecb154a0ef73ec9f329f42a7e","severity":"info","ts":"2023-02-01T20:55:15.3027199Z","version":"0.13.2-18-g7e862bc-dirty"}
launcher - version 0.13.2-18-g7e862bc-dirty
  branch:       main
  revision:     7e862bc58116421ecb154a0ef73ec9f329f42a7e
  build date:   2023-01-31
  build user:   you
  go version:   go1.19.2

launcher_gui.exe --version

To get the output of a GUI binary, we can invoke it via start, wait for the output, and redirect it.

start /B /wait launcher_gui.exe --version >> output.txt

PowerShell will automatically apply Out-String to a command's output before sending it to the input of another cmdlet, like findstr:

PS > launcher_gui.exe --version | Out-String
launcher - version 0.13.2-19-g8631e5c-dirty
  branch:       main
  revision:     8631e5c970f33bb0f859fb9819a6873c33481925
  build date:   2023-02-01
  build user:   CJ Barrett (CJHP\cjbar)
  go version:   go1.19.2
PS > launcher_gui.exe --version
PS > launcher_gui.exe --version | findstr "launcher - version"
launcher - version 0.13.2-19-g8631e5c-dirty
  build date:   2023-02-01
  go version:   go1.19.2

Testing Notes

I was unable to reproduce any bad autoupdate behavior when injecting a GUI binary into the tests for the autoupdate checkExecutable code which calls launcher --version:

• https://github.com/kolide/launcher/blob/main/pkg/autoupdate/handler.go#L98
• https://github.com/kolide/launcher/blob/main/pkg/autoupdate/findnew.go#L199
• https://github.com/kolide/launcher/blob/main/pkg/autoupdate/findnew.go#L235

I verified replacing my existing launcher installation updates dir binaries with GUI binaries still launches successfully.

Some helpful references:

https://stackoverflow.com/questions/54536/win32-gui-app-that-writes-usage-text-to-stdout-when-invoked-as-app-exe-help
https://superuser.com/questions/1198821/how-do-i-read-the-console-output-of-a-windows-gui-application
https://www.sapien.com/blog/2014/12/15/display-output-in-a-gui-application-copy/
https://devblogs.microsoft.com/oldnewthing/20090101-00/?p=19643

[directionless]

Really nice write up in the PR. Thank you