[tool] Add support for .java, .gradle, .sh, and .m files… (flutter#5567)

� to `update-excerpts` tool

Need this tool to recognize `.java`, `.gradle`, and `.sh` files in order to complete [flutter#102679](flutter#102679). The `README.md` for the `espresso` package contains code from `.java`, `.gradle`, and `.sh` files.

Support for `.m` files was requested by @tarrinneal.

Author: mike-v2

script/tool/lib/src/update_excerpts_command.dart

@@ -146,6 +146,12 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
                   case '.cpp':
                     language = 'c++';
                     break;
+                  case '.m':
+                    language = 'objectivec';
+                    break;
+                  case '.gradle':
+                    language = 'groovy';
+                    break;
                   default:
                     language = extension.substring(1);
                     break;
@@ -239,6 +245,9 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
       case 'js':
       case 'kotlin':
       case 'rfwtxt':
+      case 'java':
+      case 'groovy':
+      case 'objectivec':
       case 'swift':
         prefix = '// ';
         break;
@@ -255,6 +264,9 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
       case 'yaml':
         prefix = '# ';
         break;
+      case 'sh':
+        prefix = '# ';
+        break;
     }
     final String startRegionMarker = '$prefix#docregion $section$suffix';
     final String endRegionMarker = '$prefix#enddocregion $section$suffix';