Add support for Java 14

[eric-milles]

https://www.oracle.com/corporate/pressrelease/oracle-announces-java14-031720.html

https://www.eclipse.org/eclipse/news/4.16/jdt.php#Java14

Also, from jdt-dev mailing list:

We are pleased to announce the Java 14 support for Eclipse 2020-03 (4.15).The release notably includes the support for the following Java 14 features:
• JEP 361: Switch Expressions (Standard)
• JEP 359 : Records (Preview)
• JEP 368: Text Blocks (Second Preview)
The release can be obtained through one of the following ways:

1. P2 update site :https://download.eclipse.org/eclipse/updates/4.15-P-builds/
2. Java 14 Marketplace entry :https://marketplace.eclipse.org/content/java-14-support-eclipse-2020-03-415

Additionally, the Java 14 support will be available on 4.16 I-Builds soon to download from https://download.eclipse.org/eclipse/downloads/

Please take the bits and try out the new feature.
I would also like to take this opportunity to thank everyone involved in Java 14 Support for 4.15!