sftp subsystem ignores process umask when creating directory

### Version

2.12.0

### Bug description

Connect to mina sshd sftp server using normal sftp client. Use "mkdir" to create a directory. The directory is created with mode 777 (rwxrwxrwx). The process umask (0022 or 0027) should prevent "write by others" being set.

The directory is created with the correct mode then this is overridden in doMakeDirectory

### Actual behavior

The directory is created with mode 777 (rwxrwxrwx).

### Expected behavior

he directory is created without write by others permission.

### Relevant log output

_No response_

### Other information

_No response_

The report points to doMakeDirectory as the place where the directory mode is overridden. Start there and inspect how the SFTP subsystem creates directories and applies process umask handling. Done means an SFTP mkdir no longer grants write permission to others when the umask is 0022 or 0027, with the relevant existing SFTP tests run or extended.

Written by the indexing model from the issue text.