fix(ui-devkit) Fix generation of shared module file

[Tyratox]

Describe the bug
When generating the shared extension module the different extension modules are joined together correctly but if one extension contains multiple modules the default join inserts commas which results in a compilation error.

To Reproduce
Export multiple ngModules from one extension.

EDIT: It's the default behavior in JS: https://jsfiddle.net/kyp8L5bx/

Expected behavior
The imports should be joined together with a '' instead of a comma

[michaelbromley]

Hi, thanks for the PR!

As you might have noticed, the CI failed for no fault of your own. I just pushed a couple of fixes. Would you be so kind as to rebase onto master push again to this PR?

[Tyratox]

Of course!