Add hover states for various buttons and links

[ericbenwa]

• 3-dot dropdown in top right hover state makes the icon nearly disappear
• 3-dot dropdown icon hover state
• + button in header could use a hover state
• Save and Cancel buttons could use a hover state
• Left and right arrows for week navigation
• Q: Switch the hover weekly date range tooltip to a click instead?
• Q: Underlines on text links for hover?

[HankC138]

Q: Underlines on text links for hover?

@ericbenwa which links would we like to do this with? Project names, user names, etc? Anything and everything that redirects to another page or is there a list of specific links? I took care of the rest of the changes here except the toolTip clicking that one is gonna take a bit more.