Add support of all possible terminal color themes

**Is your feature request related to a problem? Please describe.**
I have a light theme in my terminal emulator. I can't even try lazygit because apparently it does not know abouth color themes other than default one.

**Describe the solution you'd like**
Support other color schemes.

**Describe alternatives you've considered**
Not using lazygit :(

**Additional context**
[this is unusable](https://imgur.com/a/oHzBWc8)