UI Fixes - Task Creation Dropdown

[karenever]

Some issues with items on the Task Creation dropdown:

• Colours are different for the Labels and Assignee field
• Assignee field has a different style than other dropdown inputs
• The sizes of Labels, Assignee, and Project boxes don't match the first three dropdown boxes
• In dark mode, the first three box titles are hidden

Expected Condition

1. Change the colours of the two fields to conform with the others.
2. Change the title of "Labels" to "Label"
3. Change the style of Assignee Field to match the others
4. Reduce the font size of Assignee text to match the others.
5. Fix the sizing of Labels, Assignee, and Project to match the sizes of Status, Priority, Size. All boxes should be equal.
6. Change the font colors of Status, Priority, Size to white to be visible in dark mode.
7. All the font colors of all boxes in dark mode should be the same.