Update target platform to latest 4.31-I-builds.

[rgrunber]

This introduces the following notable improvements :

• [21] JEP 430 String Templates support

• Performance improvement for "Organize Imports" when it calls "getStaticImportFavorites"

• Various refactorings to make API more accessible in jdt.core.manipulation

• Fixes "Add all imports" is inefficient when resolving static imports redhat-developer/vscode-java#3383

[rgrunber]

Just as a note, when one tries to use String templates, I do notice a lot of errors in the logs like :

!ENTRY org.eclipse.jdt.core.manipulation 4 2 2023-12-07 13:27:11.915
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.jdt.core.manipulation".
!STACK 0
java.lang.NullPointerException: Cannot invoke "org.eclipse.jdt.core.dom.Expression.getStartPosition()" because "expression" is null
	at org.eclipse.jdt.core.dom.ASTConverter.convertToVariableDeclarationFragment(ASTConverter.java:4037)
	at org.eclipse.jdt.core.dom.ASTConverter.convertToVariableDeclarationStatement(ASTConverter.java:4115)
	at org.eclipse.jdt.core.dom.ASTConverter.checkAndAddMultipleLocalDeclaration(ASTConverter.java:544)
	at org.eclipse.jdt.core.dom.ASTConverter.convert(ASTConverter.java:736)
	at org.eclipse.jdt.core.dom.ASTConverter.buildBodyDeclarations(ASTConverter.java:208)
	at org.eclipse.jdt.core.dom.ASTConverter.convert(ASTConverter.java:3439)
	at org.eclipse.jdt.core.dom.ASTConverter.convert(ASTConverter.java:1521)
	at org.eclipse.jdt.core.dom.CompilationUnitResolver.convert(CompilationUnitResolver.java:344)
	at org.eclipse.jdt.core.dom.ASTParser.internalCreateAST(ASTParser.java:1265)
	at org.eclipse.jdt.core.dom.ASTParser.createAST(ASTParser.java:867)
	at org.eclipse.jdt.core.manipulation.CoreASTProvider$1.run(CoreASTProvider.java:294)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.jdt.core.manipulation.CoreASTProvider.createAST(CoreASTProvider.java:286)
	at org.eclipse.jdt.core.manipulation.CoreASTProvider.getAST(CoreASTProvider.java:199)
	at org.eclipse.jdt.ls.core.internal.handlers.CodeActionHandler.getASTRoot(CodeActionHandler.java:356)
	at org.eclipse.jdt.ls.core.internal.handlers.CodeActionHandler.getCodeActionCommands(CodeActionHandler.java:133)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$14(JDTLanguageServer.java:765)
	at org.eclipse.jdt.ls.core.internal.BaseJDTLanguageServer.lambda$0(BaseJDTLanguageServer.java:87)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.scan(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)

Likely an issue with the AST DOM not properly handling the String template elements yet. Hover does seem to work though as well as go-to definition.