Make Lepton & LeptonX theme configurable for test-app #14405
Description
I've added a constant In the .csproj file. It can be set LeptonTheme or LeptonXTheme before running the project. Changing this constant convert entire theme of application
<PropertyGroup>
<-- ... -->
<DefineConstants>$(DefineConstants);LeptonXTheme</DefineConstants>
</PropertyGroup>
Checklist
- I fully tested it as developer / designer and created unit / integration tests
- I documented it (or no need to document or I will create a separate documentation issue)
- I worked with the design team to get their idea for UI/UX design (or no need to design for this PR)
- I've assigned reviewer, related labels and set a milestone for this PR
How to test it?
Please describe how this can be tested by the test engineers if it is not already explicit - or remove this section if no need to description.