[BUG] CI should validate built plugin file structure

[AmiStrn]

What is the bug?
If the file structure is incorrect (missing License for example) the CI passes.

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Remove file extention of License
2. Build project
3. File is missing from folder
4. Commit changes in new branch and see that CI passes.

What is the expected behavior?
CI validates files in plugin. Fails on any missing files.

[AmiStrn]

@lukas-vlcek if you are up for it let me know:)

[lukas-vlcek]

@AmiStrn I can take it. Feel free to assign it to me.