Use ADG-compliant colour set for widgets

Replace existing colours by those recommended by ADG:

• https://developer.atlassian.com/design/latest/colors.html

Scope:
tree map
cloud view
coverage bars (dashboard, package/class/file summary)
test results bars (dashboard, test results pages)
coverage markers on the page margin
class coverage distribution / class complexity diagrams (use "Blue" from ADG)
colours of hyperlinks