Update theme license logic (#2541)

Use new theme file structure
```
themes/
  [theme_name]
    [theme_name]-common.ts
    [theme_name]-light.ts
    [theme_name]-dark.ts
    LICENSE
```

Release Notes: 
- N/A
c6672dbac2Sergii Onufriienko committed on 5/31/2023, 5:36:13 PM· committed by GitHubparents584e5f751c7078
64 files changedLine totals unavailable