feat: Initialize Zastava Webhook service with TLS and Authority authentication

- Added Program.cs to set up the web application with Serilog for logging, health check endpoints, and a placeholder admission endpoint.
- Configured Kestrel server to use TLS 1.3 and handle client certificates appropriately.
- Created StellaOps.Zastava.Webhook.csproj with necessary dependencies including Serilog and Polly.
- Documented tasks in TASKS.md for the Zastava Webhook project, outlining current work and exit criteria for each task.

Mongo2Go-4.1.0/src/Mongo2Go/Helper/NetStandard21Compatibility.cs

@@ -0,0 +1,24 @@
+#if NETSTANDARD2_0
+using System;
+
+namespace Mongo2Go.Helper
+{
+    public static class NetStandard21Compatibility
+    {
+        /// <summary>
+        /// Returns a value indicating whether a specified string occurs within this <paramref name="string"/>, using the specified comparison rules.
+        /// </summary>
+        /// <param name="string">The string to operate on.</param>
+        /// <param name="value">The string to seek.</param>
+        /// <param name="comparisonType">One of the enumeration values that specifies the rules to use in the comparison.</param>
+        /// <returns><see langword="true"/> if the <paramref name="value"/> parameter occurs within this string, or if <paramref name="value"/> is the empty string (""); otherwise, <see langword="false"/>.</returns>
+        /// <exception cref="ArgumentNullException"><paramref name="value"/> is <see langword="null"/></exception>
+        public static bool Contains(this string @string, string value, StringComparison comparisonType)
+        {
+            if (@string == null) throw new ArgumentNullException(nameof(@string));
+
+            return @string.IndexOf(value, comparisonType) >= 0;
+        }
+    }
+}
+#endif