Implement switch expressions in dev/ (#139048)

I previously made a PR (#136140) that used `switch` expressions to make some parts of the Flutter codebase easier to understand. It was assigned to the framework team, and @christopherfujino let me know that it was too large to effectively review and recommended breaking it up into smaller pull requests.

Here's a PR that only targets files in the `dev/` directory. Hopefully this will be easier to work with!

(solves issue https://github.com/flutter/flutter/issues/136139)

dev/conductor/core/lib/src/repository.dart

@@ -47,12 +47,10 @@ class Remote {
 
   /// The name of the remote.
   String get name {
-    switch (_name) {
-      case RemoteName.upstream:
-        return 'upstream';
-      case RemoteName.mirror:
-        return 'mirror';
-    }
+    return switch (_name) {
+      RemoteName.upstream => 'upstream',
+      RemoteName.mirror   => 'mirror',
+    };
   }
 
   /// The URL of the remote.

dev/conductor/core/lib/src/version.dart

@@ -295,15 +295,11 @@ class Version {
 
   @override
   String toString() {
-    switch (type) {
-      case VersionType.stable:
-        return '$x.$y.$z';
-      case VersionType.development:
-        return '$x.$y.$z-$m.$n.pre';
-      case VersionType.latest:
-        return '$x.$y.$z-$m.$n.pre.$commits';
-      case VersionType.gitDescribe:
-        return '$x.$y.$z-$m.$n.pre.$commits';
-    }
+    return switch (type) {
+      VersionType.stable      => '$x.$y.$z',
+      VersionType.development => '$x.$y.$z-$m.$n.pre',
+      VersionType.latest      => '$x.$y.$z-$m.$n.pre.$commits',
+      VersionType.gitDescribe => '$x.$y.$z-$m.$n.pre.$commits',
+    };
   }
 }