Improve the names of a few commonly used APIs (#2014)

Motivation:

Naming is important; it should be clear and concise.

Modifications:

The follow renames all offer more precise names:
- Rename `server.run()` to `server.serve()`
- Rename `server.stopListening()` to `server.beginGracefulShutdown()`
- Rename `client.close()` to `client.beginGracefulShutdown()`

Result:

Clearer APIs

Author: glbrntt

Examples/v2/echo/Subcommands/Collect.swift

@@ -53,7 +53,7 @@ struct Collect: AsyncParsableCommand {
         print("collect ← \(message.text)")
       }
 
-      client.close()
+      client.beginGracefulShutdown()
     }
   }
 }

Examples/v2/echo/Subcommands/Expand.swift

@@ -53,7 +53,7 @@ struct Expand: AsyncParsableCommand {
         }
       }
 
-      client.close()
+      client.beginGracefulShutdown()
     }
   }
 }

Examples/v2/echo/Subcommands/Get.swift

@@ -48,7 +48,7 @@ struct Get: AsyncParsableCommand {
         print("get ← \(response.text)")
       }
 
-      client.close()
+      client.beginGracefulShutdown()
     }
   }
 }

Examples/v2/echo/Subcommands/Serve.swift

@@ -36,7 +36,7 @@ struct Serve: AsyncParsableCommand {
     )
 
     try await withThrowingDiscardingTaskGroup { group in
-      group.addTask { try await server.run() }
+      group.addTask { try await server.serve() }
       if let address = try await server.listeningAddress {
         print("Echo listening on \(address)")
       }

Examples/v2/echo/Subcommands/Update.swift

@@ -56,7 +56,7 @@ struct Update: AsyncParsableCommand {
         }
       }
 
-      client.close()
+      client.beginGracefulShutdown()
     }
   }
 }

Examples/v2/hello-world/Subcommands/Greet.swift

@@ -42,7 +42,7 @@ struct Greet: AsyncParsableCommand {
       }
 
       defer {
-        client.close()
+        client.beginGracefulShutdown()
       }
 
       let greeter = Helloworld_GreeterClient(wrapping: client)

Examples/v2/hello-world/Subcommands/Serve.swift

@@ -35,7 +35,7 @@ struct Serve: AsyncParsableCommand {
     )
 
     try await withThrowingDiscardingTaskGroup { group in
-      group.addTask { try await server.run() }
+      group.addTask { try await server.serve() }
       if let address = try await server.listeningAddress {
         print("Greeter listening on \(address)")
       }

Examples/v2/route-guide/Subcommands/GetFeature.swift

@@ -63,7 +63,7 @@ struct GetFeature: AsyncParsableCommand {
         print("Found '\(feature.name)' at (\(self.latitude), \(self.longitude))")
       }
 
-      client.close()
+      client.beginGracefulShutdown()
     }
   }
 }

Examples/v2/route-guide/Subcommands/ListFeatures.swift

@@ -79,7 +79,7 @@ struct ListFeatures: AsyncParsableCommand {
         }
       }
 
-      client.close()
+      client.beginGracefulShutdown()
     }
 
   }

Examples/v2/route-guide/Subcommands/RecordRoute.swift

@@ -68,7 +68,7 @@ struct RecordRoute: AsyncParsableCommand {
         """
       print(text)
 
-      client.close()
+      client.beginGracefulShutdown()
     }
   }
 }