feat(rpc): add fast-provide-root and fast-provide-wait to Add

add FastProvideRoot and FastProvideWait options to UnixfsAddSettings,
allowing RPC clients to control immediate DHT providing of root CIDs
for faster content discovery

these options default to server config (Import.FastProvideRoot and
Import.FastProvideWait) when not explicitly set by the client

client/rpc/unixfs.go

@@ -56,6 +56,14 @@ func (api *UnixfsAPI) Add(ctx context.Context, f files.Node, opts ...caopts.Unix
 		req.Option("raw-leaves", options.RawLeaves)
 	}
 
+	if options.FastProvideRootSet {
+		req.Option("fast-provide-root", options.FastProvideRoot)
+	}
+
+	if options.FastProvideWaitSet {
+		req.Option("fast-provide-wait", options.FastProvideWait)
+	}
+
 	switch options.Layout {
 	case caopts.BalancedLayout:
 		// noop, default

core/coreiface/options/unixfs.go

@@ -52,6 +52,11 @@ type UnixfsAddSettings struct {
 	PreserveMtime bool
 	Mode          os.FileMode
 	Mtime         time.Time
+
+	FastProvideRoot    bool
+	FastProvideRootSet bool
+	FastProvideWait    bool
+	FastProvideWaitSet bool
 }
 
 type UnixfsLsSettings struct {
@@ -97,6 +102,11 @@ func UnixfsAddOptions(opts ...UnixfsAddOption) (*UnixfsAddSettings, cid.Prefix,
 		PreserveMtime: false,
 		Mode:          0,
 		Mtime:         time.Time{},
+
+		FastProvideRoot:    false,
+		FastProvideRootSet: false,
+		FastProvideWait:    false,
+		FastProvideWaitSet: false,
 	}
 
 	for _, opt := range opts {
@@ -396,3 +406,23 @@ func (unixfsOpts) Mtime(seconds int64, nsecs uint32) UnixfsAddOption {
 		return nil
 	}
 }
+
+// FastProvideRoot sets whether to immediately provide root CID to DHT for faster discovery.
+// If not set, server uses Import.FastProvideRoot config value (default: true).
+func (unixfsOpts) FastProvideRoot(enable bool) UnixfsAddOption {
+	return func(settings *UnixfsAddSettings) error {
+		settings.FastProvideRoot = enable
+		settings.FastProvideRootSet = true
+		return nil
+	}
+}
+
+// FastProvideWait sets whether to block until fast provide completes.
+// If not set, server uses Import.FastProvideWait config value (default: false).
+func (unixfsOpts) FastProvideWait(enable bool) UnixfsAddOption {
+	return func(settings *UnixfsAddSettings) error {
+		settings.FastProvideWait = enable
+		settings.FastProvideWaitSet = true
+		return nil
+	}
+}