fix(amazonq): open diff in a new tab when another modal is open (aws#5289)

Author: xiaox-chen

.changes/next-release/bugfix-1a28cd4b-54eb-46bb-b0c6-2f9abc8fa9e6.json

@@ -0,0 +1,4 @@
+{
+  "type" : "bugfix",
+  "description" : "Amazon Q /doc: fix open diff in a tab when another modal is open"
+}

plugins/amazonq/chat/jetbrains-community/src/software/aws/toolkits/jetbrains/services/amazonqDoc/controller/DocController.kt

@@ -4,8 +4,10 @@
 package software.aws.toolkits.jetbrains.services.amazonqDoc.controller
 
 import com.intellij.diff.DiffContentFactory
-import com.intellij.diff.DiffManager
+import com.intellij.diff.chains.SimpleDiffRequestChain
 import com.intellij.diff.contents.EmptyContent
+import com.intellij.diff.editor.ChainDiffVirtualFile
+import com.intellij.diff.editor.DiffEditorTabFilesManager
 import com.intellij.diff.requests.SimpleDiffRequest
 import com.intellij.diff.util.DiffUserDataKeys
 import com.intellij.ide.BrowserUtil
@@ -398,7 +400,8 @@ class DocController(
                     val request = SimpleDiffRequest(message.filePath, leftDiffContent, rightDiffContent, null, null)
                     request.putUserData(DiffUserDataKeys.FORCE_READ_ONLY, true)
 
-                    DiffManager.getInstance().showDiff(project, request)
+                    val newDiff = ChainDiffVirtualFile(SimpleDiffRequestChain(request), message.filePath)
+                    DiffEditorTabFilesManager.getInstance(context.project).showDiffFile(newDiff, true)
                 }
             }