fix getRelativePathToContextRoot invoked without read-lock

[Will-ShaoHua]

Description

#5024

java.lang.Throwable: Slow operations are prohibited on EDT. See SlowOperations.assertSlowOperationsAreAllowed javadoc.
	at com.intellij.openapi.diagnostic.Logger.error(Logger.java:376)
	at com.intellij.util.SlowOperations.assertSlowOperationsAreAllowed(SlowOperations.java:106)
	at com.intellij.workspaceModel.core.fileIndex.impl.WorkspaceFileIndexDataImpl.ensureIsUpToDate(WorkspaceFileIndexDataImpl.kt:149)
	at com.intellij.workspaceModel.core.fileIndex.impl.WorkspaceFileIndexDataImpl.getFileInfo(WorkspaceFileIndexDataImpl.kt:94)
	at com.intellij.workspaceModel.core.fileIndex.impl.WorkspaceFileIndexImpl.getFileInfo(WorkspaceFileIndexImpl.kt:260)
	at com.intellij.workspaceModel.core.fileIndex.impl.WorkspaceFileIndexImpl.findFileSetWithCustomData(WorkspaceFileIndexImpl.kt:243)
	at com.intellij.openapi.roots.impl.ProjectFileIndexImpl.getContentRootForFile(ProjectFileIndexImpl.java:152)
	at com.intellij.openapi.roots.impl.ProjectFileIndexImpl.getContentRootForFile(ProjectFileIndexImpl.java:146)
	at software.aws.toolkits.jetbrains.services.codewhisperer.editor.CodeWhispererEditorUtil$getRelativePathToContentRoot$1$1$contentRoot$1.invoke(CodeWhispererEditorUtil.kt:80)
	at software.aws.toolkits.jetbrains.services.codewhisperer.editor.CodeWhispererEditorUtil$getRelativePathToContentRoot$1$1$contentRoot$1.invoke(CodeWhispererEditorUtil.kt:80)
	at com.intellij.openapi.application.ActionsKt.runReadAction$lambda$3(actions.kt:31)
	at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runReadAction$lambda$3(AnyThreadWriteThreadingSupport.kt:219)
	at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runReadAction(AnyThreadWriteThreadingSupport.kt:228)
	at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runReadAction(AnyThreadWriteThreadingSupport.kt:219)
	at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:852)
	at com.intellij.openapi.application.ActionsKt.runReadAction(actions.kt:31)
	at software.aws.toolkits.jetbrains.services.codewhisperer.editor.CodeWhispererEditorUtil.getRelativePathToContentRoot(CodeWhispererEditorUtil.kt:80)
	at software.aws.toolkits.jetbrains.services.codewhisperer.toolwindow.CodeWhispererCodeReferenceManager.insertCodeReference(CodeWhispererCodeReferenceManager.kt:73)
	at software.aws.toolkits.jetbrains.services.cwc.controller.ReferenceLogController.addReferenceLog(ReferenceLogController.kt:36)
	at software.aws.toolkits.jetbrains.services.cwc.inline.InlineChatController$processNewCode$1$4.invoke(InlineChatController.kt:318)
	at software.aws.toolkits.jetbrains.services.cwc.inline.InlineChatController$processNewCode$1$4.invoke(InlineChatController.kt:314)
	at software.aws.toolkits.jetbrains.services.cwc.inline.InlineChatController$diffAcceptHandler$1$1.invokeSuspend(InlineChatController.kt:173)

License

I confirm that my contribution is made under the terms of the Apache 2.0 license.

[Will-ShaoHua]

incorrect, will update PR