project: reorganize the structure of the project.

* remove dotnet-tool.json because the project does not rely on any dotnet tools.
* remove Directory.Build.props because the solution has only one project.
* move src/SourceGit to src. It's not needed to put all sources into a subfolder of src since there's only one project.

src/Models/Remote.cs

@@ -0,0 +1,49 @@
+using System.Text.RegularExpressions;
+
+namespace SourceGit.Models
+{
+    public partial class Remote
+    {
+
+        [GeneratedRegex(@"^http[s]?://([\w\-]+@)?[\w\.\-]+(\:[0-9]+)?/[\w\-]+/[\w\-\.]+\.git$")]
+        private static partial Regex regex1();
+
+        [GeneratedRegex(@"^[\w\-]+@[\w\.\-]+(\:[0-9]+)?:[\w\-]+/[\w\-\.]+\.git$")]
+        private static partial Regex regex2();
+        [GeneratedRegex(@"^ssh://([\w\-]+@)?[\w\.\-]+(\:[0-9]+)?/[\w\-]+/[\w\-\.]+\.git$")]
+        private static partial Regex regex3();
+
+        private static readonly Regex[] URL_FORMATS = [
+            regex1(),
+            regex2(),
+            regex3(),
+        ];
+
+        public string Name { get; set; }
+        public string URL { get; set; }
+
+        public static bool IsSSH(string url)
+        {
+            if (string.IsNullOrWhiteSpace(url))
+                return false;
+
+            for (int i = 1; i < URL_FORMATS.Length; i++)
+            {
+                if (URL_FORMATS[i].IsMatch(url))
+                    return true;
+            }
+
+            return false;
+        }
+
+        public static bool IsValidURL(string url)
+        {
+            foreach (var fmt in URL_FORMATS)
+            {
+                if (fmt.IsMatch(url))
+                    return true;
+            }
+            return false;
+        }
+    }
+}