Windows: add win attrs support;

[chenjie4255]

close #5693

Background

• When setting attributes for a file or folder, winfsp call juicefs.chflags() and pass the attribute flags to juicefs.
• According to this article, on windows sytem, the readonly attribute for a folder basically doesn't have any effect.

Test

run winfsp-test --fuse-external create*

• before this PR, it failed for the create_fileattr_test and create_readonly_test.
• after this PR, the failed tests passed. [tested on redis and sqlite, didn't test on tikv]

Discussion

• Maybe we can ignore the FlagWindowsArchive? This is not used by any modern system accroding to this topic. but if we want to align the behavior of samba client for windows, this should be kept.

[chenjie4255]

In the latest commit, the behavior of the read-only attribute has been aligned with the unix system (even for directories).