Document vsce as a development requirement

[auxym]

Describe the bug

Sorry, I'm new to developing VS Code extensions :)

I read and followed the contribution guide, but failed to package the extension. Upon investigation, I found:

vsce: command not found

After running npm install -g @vscode/vsce I was able to successfully run the package task and create the VSIX file.

I would have created a PR for this, but I'm not sure if the vsce requirement should go in package.json, in build.sh (run the npm install command) or simply documented as a requirement in the contribution guide. If you let me know your preference I can submit a quick PR.

To Reproduce

• Fresh install of vscode/npm/dotnet SDK
• Follow the contribution guide

Avalonia for VS Code

master branch

Avalonia version

NA

VS Code version

1.95.3

Relevant log output

Creating output directory: C:\Users\thef2102\source\AvaloniaVSCode/output/
Packaging extension to C:\Users\thef2102\source\AvaloniaVSCode/output/
C:\Users\thef2102\source\AvaloniaVSCode/.vscode/package.sh: line 23: vsce: command not found
 *  Terminal will be reused by tasks, press any key to close it.

Additional context

No response

[MikeCodesDotNET]

Fixed.