Project Manager doesn't need to search the main methods if a project doesn't have the Java nature

Steps to reproduce:

• start VS Code with Extension Pack for Java v0.29.2024091906 (pre-release)
• import the weblaf project

You will see the following exception:

[Error - 4:26:05 AM] Nov 16, 2024, 4:26:05?AM Problems occurred when invoking code from plug-in: "org.eclipse.jdt.ls.core".
weblaf-parent does not exist
Java Model Exception: Error in Java Model (code 969): weblaf-parent does not exist
	at org.eclipse.jdt.internal.core.JavaElement.newNotPresentException(JavaElement.java:546)
	at org.eclipse.jdt.internal.core.JavaModelManager.getPerProjectInfoCheckExistence(JavaModelManager.java:2535)
	at org.eclipse.jdt.internal.core.JavaProject.getPerProjectInfo(JavaProject.java:2329)
	at org.eclipse.jdt.internal.core.JavaProject.getResolvedClasspath(JavaProject.java:2402)
	at org.eclipse.jdt.internal.core.JavaProject.getAllPackageFragmentRoots(JavaProject.java:1774)
	at org.eclipse.jdt.internal.core.JavaProject.getAllPackageFragmentRoots(JavaProject.java:1765)
	at com.microsoft.jdtls.ext.core.ProjectCommand.getMainClasses(ProjectCommand.java:243)
	at com.microsoft.jdtls.ext.core.CommandHandler.executeCommand(CommandHandler.java:35)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler$1.run(WorkspaceExecuteCommandHandler.java:230)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler.executeCommand(WorkspaceExecuteCommandHandler.java:220)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$4(JDTLanguageServer.java:609)
	at org.eclipse.jdt.ls.core.internal.BaseJDTLanguageServer.lambda$0(BaseJDTLanguageServer.java:87)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:690)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:527)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:507)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1458)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:2034)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:189)

从异常中指出的入口 ProjectCommand.getMainClasses 开始，并使用指定版本的 VS Code Java 扩展导入链接的 weblaf 项目来重现问题。完成标准是：在搜索主类时，导入不具有 Java nature 的项目不再触发缺少项目异常。