Bump to Eclipse 2023 06

[dvojtise]

Description

Upgrade the base Eclipse to Eclipse 2023-06. Applies the changes required by the new version of components (XText, Xtend, Sirius) New minimal requirement : java 17

Changes

• Use java 17 in the CI docker image
• new splash screen
• use tycho 3.0.4
• use xtend 2.31
• use lsp4j 0.21
• change maven plugin for generating plantuml images
• fix melangeK3FSM project nature
• remove use of deprecated xtext.MergeableManifest

Contribution to issues

Contribute to #298

Companion Pull Requests

• https://github.com/eclipse/gemoc-studio/pull/299
• https://github.com/eclipse/gemoc-studio-modeldebugging/pull/232
• https://github.com/eclipse/gemoc-studio-execution-ale/pull/61
• https://github.com/eclipse/gemoc-studio-execution-java/pull/32
• https://github.com/eclipse/gemoc-studio-execution-moccml/pull/77
• https://github.com/eclipse/gemoc-studio-moccml/pull/28
• https://github.com/eclipse/gemoc-studio-commons/pull/4