Move to JDK 17

[jurgenvinju]

This is to start the work on an integral move to JDK 17 for all usethesource projects and the dependent libraries that are not on use the source.

The motivation is to keep up to date. In fact several of the libraries we depend on in library projects do not release versions of their class files anymore before JDK 17.

This means we go to JDK 17 as run-time JVM target and as source language. We can start using Java 17 features.

It has to go in one big bang because newer JDK 17 class files are not compatible with older Java 11 run-times.

Core:

• [ ] capsule
• [ ] vallang
• [ ] rascal
• [ ] rascal-maven-plugin
• [ ] rascal-eclipse
• [ ] rascal-language-servers
• [ ] rascal-core
• [ ] typepal

Libraries:

• [ ] clair
• [ ] flybytes
• [ ] php-analysis
• [ ] rascal-git

[jurgenvinju]

The branch name shall be upgrade-jdk17 on all packages