Update icons to official branding colors

[dvojtise]

This PR changes all remaining icons to the Eclipse official colors for GEMOC

It also does some minor presentation fixes in the official example in order to look like the other existing ones.

This PR comes with

• https://github.com/eclipse/gemoc-studio/pull/160
• https://github.com/eclipse/gemoc-studio-modeldebugging/pull/110
• https://github.com/eclipse/gemoc-studio-execution-moccml/pull/14