Refactor: Rename GetDynamicAsync to GetAsync

Renamed `GetDynamicAsync` to `GetAsync` across `ProfileApi.cs`,
`RecActionApi.cs`, and `ResultApi.cs` to improve consistency
and align with naming conventions for asynchronous methods.

Updated XML documentation to clarify that the non-generic
`GetAsync` overload returns a dynamically deserialized payload,
typically a `System.Text.Json.JsonElement`. Highlighted its
relation to the generic `GetAsync<T>` method.

Adjusted method signatures for both `NETFRAMEWORK` and
non-`NETFRAMEWORK` code paths. Updated test files
(`ProfileApiTests.cs`, `RecActionApiTests.cs`, and
`ResultApiTests.cs`) to reflect the renaming, including
test method names and assertions.

These changes enhance code readability, maintainability,
and consistency.

tests/ReC.Tests/Client/ResultApiTests.cs

@@ -38,14 +38,14 @@ public class ResultApiTests : RecClientTestBase
     }
 
     [Test]
-    public async Task GetDynamicAsync_without_filters_returns_dynamic_payload_or_throws_not_found()
+    public async Task GetAsync_non_generic_returns_dynamic_payload_or_throws_not_found()
     {
         var (client, scope) = CreateScopedClient();
         using var _ = scope;
 
         try
         {
-            dynamic results = await client.Results.GetDynamicAsync();
+            dynamic? results = await client.Results.GetAsync();
             Assert.That(results, Is.Not.Null);
             Assert.That(results, Is.TypeOf<JsonElement>());
         }