feat: introduce models to represent atproto id

tests/StevanFreeborn.Atproto.IdentityResolver.Tests/AtprotoIdTests.cs

@@ -0,0 +1,19 @@
+namespace StevanFreeborn.Atproto.IdentityResolver.Tests;
+
+public class AtprotoIdTests
+{
+  [Theory]
+  [InlineData("")]
+  [InlineData("localhost")]
+  [InlineData("did:web:")]
+  [InlineData("did:plc:")]
+  [InlineData("did:mu:dxbmien5xsrkov5yhywgc4zu")]
+  [InlineData("@stevanfreeborn.com")]
+  [InlineData(null)]
+  public void From_WhenCalledWithInvalidDid_ItShouldThrowInvalidArgumentException(string? atprotoId)
+  {
+    var act = () => AtprotoId.From(atprotoId!);
+
+    act.Should().Throw<ArgumentException>();
+  }
+}