fuse: add FUSE performance options to weed fuse command (#7925)

This adds support for the new FUSE performance options to the 'weed fuse' command,
matching the functionality available in 'weed mount'.

Added options:
- writebackCache: Enable FUSE writeback cache for improved write performance
- asyncDio: Enable async direct I/O for better concurrency
- cacheSymlink: Enable symlink caching to reduce metadata lookups
- sys.novncache: (macOS only) Disable vnode name caching to avoid stale data

These options can now be used with mount -t weed:
  mount -t weed fuse /mnt -o "filer=localhost:8888,writebackCache=true,asyncDio=true"

This ensures feature parity between 'weed mount' and 'weed fuse' commands.

weed/command/mount_std.go

@@ -208,7 +208,7 @@ func RunMount(option *MountOptions, umask os.FileMode) bool {
 		if runtime.GOARCH == "amd64" {
 			fuseMountOptions.Options = append(fuseMountOptions.Options, "noapplexattr")
 		}
-		if *option.novncache {
+		if option.novncache != nil && *option.novncache {
 			fuseMountOptions.Options = append(fuseMountOptions.Options, "novncache")
 		}
 		fuseMountOptions.Options = append(fuseMountOptions.Options, "slow_statfs")
@@ -216,13 +216,13 @@ func RunMount(option *MountOptions, umask os.FileMode) bool {
 		fuseMountOptions.Options = append(fuseMountOptions.Options, fmt.Sprintf("iosize=%d", ioSizeMB*1024*1024))
 	}
 
-	if *option.writebackCache {
+	if option.writebackCache != nil && *option.writebackCache {
 		fuseMountOptions.Options = append(fuseMountOptions.Options, "writeback_cache")
 	}
-	if *option.asyncDio {
+	if option.asyncDio != nil && *option.asyncDio {
 		fuseMountOptions.Options = append(fuseMountOptions.Options, "async_dio")
 	}
-	if *option.cacheSymlink {
+	if option.cacheSymlink != nil && *option.cacheSymlink {
 		fuseMountOptions.EnableSymlinkCaching = true
 	}