Switch to tycho 4.0.3 and Java 17

After #794 (closed) we should consider moving to Tycho 4.0.3 and JavaSE-17 for builds.

It is also possible to switch Simantics to JavaSE-17 for source/target compatibility as well.

Benefits would include:

• General VM/GC performance improvements (e.g. https://kstefanj.github.io/2021/11/24/gc-progress-8-17.html)
• Plenty of syntactic sugar
• More informative NullPointerExceptions
  • This is already attained by just using JRE 17 as a runtime
• instanceof pattern matching (if (s instanceof Rectangle2D r) ...)
• More pattern matching everywhere
• records
• ...

Tycho 3.x includes support for mixed products defined using both features and plug-ins, which is supported also in the Eclipse IDE after the 2023-09 release.