Color scheme customization in Saka

[pureooze]

As mentioned in #23 users could find it useful to change the color scheme of Saka. Ideally this is implemented as a drop down that lets users select the theme they desire.

[pureooze]

Some words of caution with implementing this:
In my opinion this is not a high priority feature and may require a significant time commitment and a lot of unneeded complexity to the codebase. It can also be difficult to test this so it is a good idea to get Saka working with Storybook/UI Testing before attempting this.