chore: stub out resolver which will be main entry point of the package

src/StevanFreeborn.Atproto.IdentityResolver/IResolver.cs

@@ -0,0 +1,12 @@
+namespace StevanFreeborn.Atproto.IdentityResolver;
+
+/// <summary>
+///
+/// </summary>
+public interface IResolver
+{
+  /// <summary>
+  ///
+  /// </summary>
+  Task<DidDocument> ResolveOrThrowAsync(AtprotoId atprotoId, CancellationToken ct);
+}

src/StevanFreeborn.Atproto.IdentityResolver/Resolver.cs

@@ -0,0 +1,35 @@
+namespace StevanFreeborn.Atproto.IdentityResolver;
+
+/// <inheritdoc />
+public class Resolver : IResolver
+{
+  /// <inheritdoc />
+  public Task<DidDocument> ResolveOrThrowAsync(AtprotoId atprotoId, CancellationToken ct)
+  {
+    // you need to retrieve the did document based on what you got
+    // if you have domain
+    //   you are going to try to retrieve the did
+    //   either through using /.well-known/did.json
+    //   or looking for _atproto.domain txt record
+    //
+    // you now for sure have a did
+    //   check method
+    //     if method is web
+    //        retrieve doc from domain/.well-known/did.json
+    //     if method is plc
+    //        retrieve doc from plc.directory/{did}
+    //   you now have the document
+    //     extract alsoKnownAs which is the handle
+    //       make sure you can get back the same did
+    //       from the handle's domain at /.well-known/did.json
+    //       or _atproto.domain txt record
+
+    return Task.FromResult(new DidDocument());
+  }
+
+}
+
+/// <summary>
+///
+/// </summary>
+public class DidDocument();