Use git ls-files to find DLLs to index

csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/Git.cs

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+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+
+namespace Semmle.Extraction.CSharp.DependencyFetching
+{
+    /// <summary>
+    /// Utilities for querying information from the git CLI.
+    /// </summary>
+    internal class Git
+    {
+        private readonly ProgressMonitor progressMonitor;
+        private const string git = "git";
+
+        public Git(ProgressMonitor progressMonitor)
+        {
+            this.progressMonitor = progressMonitor;
+        }
+
+        /// <summary>
+        /// Lists all files matching <paramref name="pattern"/> which are tracked in the
+        /// current git repository.
+        /// </summary>
+        /// <param name="pattern">The file pattern.</param>
+        /// <returns>A list of all tracked files which match <paramref name="pattern"/>.</returns>
+        /// <exception cref="Exception"></exception>
+        public List<string> ListFiles(string pattern)
+        {
+            var results = new List<string>();
+            var args = string.Join(' ', "ls-files", $"\"{pattern}\"");
+
+            progressMonitor.RunningProcess($"{git} {args}");
+            var pi = new ProcessStartInfo(git, args)
+            {
+                UseShellExecute = false,
+                RedirectStandardOutput = true
+            };
+
+            using var p = new Process() { StartInfo = pi };
+            p.OutputDataReceived += new DataReceivedEventHandler((sender, e) =>
+            {
+                if (!string.IsNullOrWhiteSpace(e.Data))
+                {
+                    results.Add(e.Data);
+                }
+            });
+            p.Start();
+            p.BeginOutputReadLine();
+            p.WaitForExit();
+
+            if (p.ExitCode != 0)
+            {
+                progressMonitor.CommandFailed(git, args, p.ExitCode);
+                throw new Exception($"{git} {args} failed");
+            }
+
+            return results;
+        }
+
+    }
+}