Add New Row and Column Manipulation Features to FileFormat.Cells

- Implement InsertRow, InsertRows, HideRows, UnhideRows, HideColumns, and UnhideColumns methods.
- Enhance the Worksheet class to support advanced row and column operations, improving the library's functionality.
- Ensure robust error handling and input validation for new methods.
- Update API documentation for added methods, providing clear usage instructions.

These updates introduce significant enhancements to the FileFormat.Cells library, allowing for more versatile manipulation of rows and columns in Excel worksheets.

Author: Fahad Adeel

FileFormat.Cells/Comment.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace FileFormat.Cells
+{
+    public class Comment
+    {
+        public string Author { get; set; }
+        public string Text { get; set; }
+
+        public Comment(string author, string text)
+        {
+            Author = author;
+            Text = text;
+        }
+    }
+}

FileFormat.Cells/FileFormat.Cells.csproj

@@ -2,7 +2,8 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+	  <LangVersion>10.0</LangVersion>  
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>