Fix build

[Koenkk]

This merge requests fixes the build failing on a fresh checkout.

There are two reasons why it fails:

• The latest vsce requires Node 14+ (build fails on Node 10 due to vsce using the unsupported nullish coalescing operator). Source: https://github.com/microsoft/vscode-vsce#requirements
• In addition the script location has been changed (node_modules/vsce/out/vsce -> node_modules/vsce/vsce)

[cdietrich]

Please pr/check the 226 wip branch

[cdietrich]

somehow does not work https://github.com/itemis/xtext-languageserver-example/runs/4802794411?check_suite_focus=true arr ggg i just changed half

looks like we have multiple script calls in the build. you change only one

[Koenkk]

@cdietrich thanks for merging, really appreciate this example!