Fix dark theme colors and overflowing rounded corners for the project import pages

[gtsiolis]

Problem to solve

Some components on the project import pages added back in #4443 are not using appropriate colors for the dark theme and border radius is overflowing for some elements.

Although there are no design specs for these specific elements in dark mode, it could be relatively easy to reuse the same border colors as the rest of the product when using dark theme and remove the overflowing rounded corners.

Select Repository	Select Team	Projects List

[jankeromnes]

This can be achieved by always adding a overflow-hidden class next to the rounded-xl class on the containers.

[gtsiolis]

Thanks for taking a look at this @jankeromnes! Most design issues here have been resolved with the changes in #5120 and #5098 as some nested elements with rounded corners have been removed and colors have been updated.

Added #5481 to resolve the rest of the minor issues here.

Couldn't make overflow-hidden work but maybe I've missed something. Tried using rounded-t-xl when needed. Although these are still suffering from the same issue as is #5086. However, all these issues would be resolved with #4951. 💡