Move client's options to separate files

This should help in discovering the available options for a given object.

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

client_opts.go

@@ -0,0 +1,77 @@
+package containerd
+
+import (
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/remotes"
+	"google.golang.org/grpc"
+)
+
+type clientOpts struct {
+	defaultns   string
+	dialOptions []grpc.DialOption
+}
+
+// ClientOpt allows callers to set options on the containerd client
+type ClientOpt func(c *clientOpts) error
+
+// WithDefaultNamespace sets the default namespace on the client
+//
+// Any operation that does not have a namespace set on the context will
+// be provided the default namespace
+func WithDefaultNamespace(ns string) ClientOpt {
+	return func(c *clientOpts) error {
+		c.defaultns = ns
+		return nil
+	}
+}
+
+// WithDialOpts allows grpc.DialOptions to be set on the connection
+func WithDialOpts(opts []grpc.DialOption) ClientOpt {
+	return func(c *clientOpts) error {
+		c.dialOptions = opts
+		return nil
+	}
+}
+
+// RemoteOpts allows the caller to set distribution options for a remote
+type RemoteOpts func(*Client, *RemoteContext) error
+
+// WithPullUnpack is used to unpack an image after pull. This
+// uses the snapshotter, content store, and diff service
+// configured for the client.
+func WithPullUnpack(client *Client, c *RemoteContext) error {
+	c.Unpack = true
+	return nil
+}
+
+// WithPullSnapshotter specifies snapshotter name used for unpacking
+func WithPullSnapshotter(snapshotterName string) RemoteOpts {
+	return func(client *Client, c *RemoteContext) error {
+		c.Snapshotter = snapshotterName
+		return nil
+	}
+}
+
+// WithSchema1Conversion is used to convert Docker registry schema 1
+// manifests to oci manifests on pull. Without this option schema 1
+// manifests will return a not supported error.
+func WithSchema1Conversion(client *Client, c *RemoteContext) error {
+	c.ConvertSchema1 = true
+	return nil
+}
+
+// WithResolver specifies the resolver to use.
+func WithResolver(resolver remotes.Resolver) RemoteOpts {
+	return func(client *Client, c *RemoteContext) error {
+		c.Resolver = resolver
+		return nil
+	}
+}
+
+// WithImageHandler adds a base handler to be called on dispatch.
+func WithImageHandler(h images.Handler) RemoteOpts {
+	return func(client *Client, c *RemoteContext) error {
+		c.BaseHandlers = append(c.BaseHandlers, h)
+		return nil
+	}
+}