controller: remove controller grpc service

Remove the controller grpc service along with associated code related to
sessions or remote controllers.

Data types that are still used with complicated dependency chains have
been kept in the same package for a future refactor.

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

controller/controller.go

@@ -2,35 +2,12 @@ package controller
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/docker/buildx/controller/control"
 	"github.com/docker/buildx/controller/local"
-	"github.com/docker/buildx/controller/remote"
-	"github.com/docker/buildx/util/progress"
 	"github.com/docker/cli/cli/command"
-	"github.com/pkg/errors"
 )
 
-func NewController(ctx context.Context, opts control.ControlOptions, dockerCli command.Cli, pw progress.Writer) (control.BuildxController, error) {
-	var name string
-	if opts.Detach {
-		name = "remote"
-	} else {
-		name = "local"
-	}
-
-	var c control.BuildxController
-	err := progress.Wrap(fmt.Sprintf("[internal] connecting to %s controller", name), pw.Write, func(l progress.SubLogger) (err error) {
-		if opts.Detach {
-			c, err = remote.NewRemoteBuildxController(ctx, dockerCli, opts, l)
-		} else {
-			c = local.NewLocalBuildxController(ctx, dockerCli, l)
-		}
-		return err
-	})
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to start buildx controller")
-	}
-	return c, nil
+func NewController(ctx context.Context, dockerCli command.Cli) control.BuildxController {
+	return local.NewLocalBuildxController(ctx, dockerCli)
 }