Improve UI

[GenericConfluent]

Task

(Don't worry about the fact that the Desired courses are at the bottom of the right panel, that an effect from a local change I'm not going to be pushing yet as I work on the GraphWidget)
Spacing and alignment:

• Align the two buttons in the top so that they are vertically centered like the text.
• Add spacing around left and right sides of the text input. (Could do all sides too)
• Add the same amount of spacing for the desired course list, and then increase it so that the text input is wider than rows for the listed courses.
• Make the spacing for the desired and required courses equivalent.

Colour:

• Make the background colour of the icon buttons in the top right transparent and make the text the blue colour of the current background.
• Delete icons should also have a transparent background colour but be a warm colour (red is good), pull it from the pallet.