Add SFTP support to gpfdist for data ingestion

Feature:Supporting the Loading of bz(bz2) Format Files

gpfdist, Cloudberry's parallel file distribution program,
traditionally required data files to be co-located with the gpfdist
process. This limitation made it cumbersome to load data from remote
servers, often requiring an extra data transfer step.

This commit extends gpfdist to support the SFTP protocol, enabling
users to ingest data directly from remote servers. This enhancement
streamlines ETL workflows by allowing `CREATE EXTERNAL TABLE` to specify
SFTP locations.

Key change information:
Implement the loading of .bz2 files by utilizing the read functions
provided by the libssh2 library.

Author: 王平10304955

src/backend/utils/misc/fstream/gfile.c

@@ -244,7 +244,7 @@ bz_file_read(gfile_t *fd, void *ptr, size_t len)
 			if (fd->is_sftp)
 			{
 #ifdef LIBSSH2
-				gfile_printf_then_putc_newline("sftp_rean : Read bz files from an SFTP server");
+				gfile_printf_then_putc_newline("sftp_read : Read bz files from an SFTP server");
 				s = sftp_read(fd, z->in + z->in_size, sizeof z->in - z->in_size);
 #endif
 			}