[FEAT]: Custom Properties (#2933)

* add custom properties model and clients

* observable

* observable tests

* add search

* error CS8370: 'target-typed object creation'

* Error CS8370: 'target-typed object creation'

* add patch with body that return status code

* fixes for failed ConventionTests

* working UnitTests

* (de)serialization and model tests

* Update Repository.cs

Octokit/Clients/IRepositoryCustomPropertiesClient.cs

@@ -0,0 +1,36 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace Octokit
+{
+    /// <summary>
+    /// A client for GitHub's Repository Custom Property Values API.
+    /// </summary>
+    /// <remarks>
+    /// See the <a href="https://docs.github.com/rest/repos/custom-properties">Custom Properties API documentation</a> for more information.
+    /// </remarks>
+    public interface IRepositoryCustomPropertiesClient
+    {
+        /// <summary>
+        /// Get all custom property values for a repository.
+        /// </summary>
+        /// <remarks>
+        /// See the <a href="https://docs.github.com/rest/repos/custom-properties#get-all-custom-property-values-for-a-repository">API documentation</a> for more information.
+        /// </remarks>
+        /// <param name="owner">The owner of the repository.</param>
+        /// <param name="repoName">The name of the repository.</param>
+        [ExcludeFromPaginationApiOptionsConventionTest("Pagination not supported by GitHub API (tested 15/06/2024)")]
+        Task<IReadOnlyList<CustomPropertyValue>> GetAll(string owner, string repoName);
+
+        /// <summary>
+        /// Create new or update existing custom property values for a repository. Using a value of null for a custom property will remove or 'unset' the property value from the repository.
+        /// </summary>
+        /// <remarks>
+        /// See the <a href="https://docs.github.com/rest/repos/custom-properties#create-or-update-custom-property-values-for-a-repository">API documentation</a> for more information.
+        /// </remarks>
+        /// <param name="owner">The owner of the repository</param>
+        /// <param name="repoName">The name of the repository</param>
+        /// <param name="propertyValues">The custom property values to create or update</param>
+        Task CreateOrUpdate(string owner, string repoName, UpsertRepositoryCustomPropertyValues propertyValues);
+    }
+}