Refresh Thread bug fixes, add offline support for stateful end user c…

…lient. (#63)

* Add xml docs

* Move refresh logic to class. Fixes.

Moved refresh logic to another class. Now the thread gets turned on/off automatically per auth state changes. Commit looks noisy than should because of format tweaks, sorry. :/

* XML doc. Remove redundant auth state notification.

* xml doc

* Moved token refresh logic here.

* Add expired token test

* Add log in/log out test

* Add maximum refresh wait time

* Add utility to check if the session has expired

All of the calls to check for expiration in the current implementation were checking to see if the session had expired.

* Adding Unity samples

* Add support for online/offline

* Method name to match RetrieveSessionAsync();

* Added description of updates

Gotrue/Api.cs

@@ -14,6 +14,9 @@
 
 namespace Supabase.Gotrue
 {
+	/// <summary>
+	/// The REST calls to the Gotrue API.
+	/// </summary>
 	public class Api : IGotrueApi<User, Session>
 	{
 		private string Url { get; }
@@ -25,6 +28,9 @@ public class Api : IGotrueApi<User, Session>
 		public Func<Dictionary<string, string>>? GetHeaders { get; set; }
 
 		private Dictionary<string, string> _headers;
+		/// <summary>
+		/// Headers to be sent with every request. These will be merged with any headers returned by GetHeaders.
+		/// </summary>
 		protected Dictionary<string, string> Headers
 		{
 			get => GetHeaders != null ? GetHeaders().MergeLeft(_headers) : _headers;
@@ -585,6 +591,10 @@ public Task<BaseResponse> DeleteUser(string uid, string jwt)
 			return Helpers.MakeRequest(HttpMethod.Delete, $"{Url}/admin/users/{uid}", data, CreateAuthedRequestHeaders(jwt));
 		}
 
+		/// <summary>
+		/// Calls the GoTrue server to get the settings (for example, if email auto confirmation is turned on)
+		/// </summary>
+		/// <returns></returns>
 		public Task<Settings?> Settings()
 		{
 			return Helpers.MakeRequest<Settings>(HttpMethod.Get, $"{Url}/settings", null, Headers);