This is a meta issue to track bootstrapping a Dart backend for sidekick (this is intended to track initial, early work on a generator).

• land a hello-world generator (generating mostly empty files)
• the main library file for package:google_client_api should be called api.dart (not client.dart)
• emit enums
• handle emitting primitive types to dart types (string, int32, int64, ...)
• emit messages
• create a WKT for google.protobuf.FieldMask
• create a WKT for google.protobuf.Duration
• add basic tests for the implementation
• emit service method calls
• escape dart keywords
• create a WKT for google.protobuf.Any
• Implement the mapping of uint64 and int64 in JSON #1568
• create a WKT for google.protobuf.Timestamp #1569
• generate google/cloud/location #1570
• generate google/iam #1571
• Any - add custom support for unpackaging errors from Status.details #1572
• Any - add custom support for LROs (the operation result and the metadata) #1573
• support types that have custom encodings #1574
• improve the generated dartdocs - resolve [name][reference] links to [reference] google-cloud-dart#25