Bump eclipse 2021 12

[dvojtise]

Description

Bump Eclipse base IDE to 2021-12 use corresponding tycho (2.5.0) and xtend/xtext (2.25.0)

Companion Pull Requests

• https://github.com/eclipse/gemoc-studio/pull/255
• https://github.com/eclipse/gemoc-studio-modeldebugging/pull/213
• https://github.com/eclipse/gemoc-studio-execution-java/pull/23
• https://github.com/eclipse/gemoc-studio-moccml/pull/23
• https://github.com/eclipse/gemoc-studio-execution-moccml/pull/65