Merging event/calendar colors

[niccokunzmann]

Is your feature request related to a problem? Please describe.

Calendars can have colors and events can have colors.
These should be taken into consideration when merging.

X-APPLE-CALENDAR-COLOR:#e78074
X-COLOR
COLOR

Describe alternatives you've considered

nothing

Additional context

niccokunzmann/open-web-calendar#105
niccokunzmann/open-web-calendar#88

Code of Conduct

• I agree to follow this project's Code of Conduct

Are you willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time, and I know how to start.
• Yes, I have the time, but I don't know how to start. I would need guidance.
• No, I don't have the time, although I believe I could do it if I had the time...
• No, I don't have the time and I wouldn't even know how to start.