FileManager: Add Overview (#7601)

Author: arman-boyakhchyan

concepts/05 UI Components/FileManager/05 Overview/00 Overview.md

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+DevExtreme FileManager is an interactive component that allows users to view and manage files and directories. The component supports editing, deleting, and uploading operations.
+
+This overview highlights FileManager elements, key features, and what to explore next.

concepts/05 UI Components/FileManager/05 Overview/05 Elements.md

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+<img src="/images/FileManager/filemanager-elements.png" alt="FileManager elements"/>
+
+1. [Toolbar](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/toolbar/)
+2. [Root Folder](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/#rootFolderName)
+3. **Child Folder**
+4. **Item View Header**
+5. [Item View Column Headers](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/itemView/details/columns/)
+6. [Items](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/itemView/)

concepts/05 UI Components/FileManager/05 Overview/10 Key Features.md

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+- **File System Support**    
+The DevExtreme FileManager supports [in-memory](/Documentation/ApiReference/UI_Components/dxFileManager/File_System_Providers/Object/) (JSON), [remote](/Documentation/ApiReference/UI_Components/dxFileManager/File_System_Providers/Remote/), and [custom](/Documentation/ApiReference/UI_Components/dxFileManager/File_System_Providers/Custom/) file system provider types.
+
+- **Cloud Service Integration**    
+You can implement the custom file system provider type to connect FileManager to a cloud service provider (for instance, [Amazon S3](/Documentation/Guide/Common/Integration_Guides/Manage_Amazon_S3_Storage_with_DevExtreme_Components/#FileManager) or [Azure Blob](/Documentation/Guide/Common/Integration_Guides/Manage_Azure_Blob_Storage_with_DevExtreme_Components/#FileManager)).
+
+- **Detail and Thumbnail Views**    
+FileManager supports two file representation modes: "Thumbnails" and "Details". "Thumbnails" displays only thumbnails, while "Details" includes [additional information](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/itemView/details/). Users can switch between the two options in the FileManager [toolbar](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/toolbar/).
+
+- **Configurarble Permissions**     
+DevExtreme FileManager allows you to configure [permissions](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/permissions/) to manage user access to files. You can enable/disable operations such as file upload/download, creation, and deletion.
+
+- **File Uploading**    
+You can configure upload options such as [maximum file size](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/upload/#maxFileSize) and [chunk uploading](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/upload/#chunkSize). Users can upload files through drag and drop operations or in the component toolbar.
+
+- **Adaptability**    
+DevExtreme FileManager fits screens of all sizes and ships with right-to-left ([RTL](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/#rtlEnabled)) representation support.
+
+- **Customization**    
+FileManager allows you to customize visual elements such as [file thumbnails](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/#customizeThumbnail) and toolbar [items](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/toolbar/items/).
+
+- **Data Selection**    
+FileManager supports single and multiple [selection modes](/Documentation/ApiReference/UI_Components/dxFileManager/Configuration/#selectionMode). The following image demonstrates available FileManager item states:    
+<img src="/images/FileManager/filemanager-item-states.png" alt="FileManager item states"/>
+    1. **Selected Item**
+    2. **Selected and Focused**
+    3. **Hover State**
+    4. **Default State**
+    5. **Focused Item**

concepts/05 UI Components/FileManager/05 Overview/15 Explore More.md

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+- [Getting Started with FileManager](/Documentation/Guide/UI_Components/FileManager/Getting_Started_with_File_Manager/)
+
+- [API](/Documentation/ApiReference/UI_Components/dxFileManager/)
+
+- [Demos](https://js.devexpress.com/Demos/WidgetsGallery/Demo/FileManager/Overview/)