Fix Master AES key rotation on Windows
Fix Master AES key rotation on Windows

Two issues causing this:
- On Windows, `stats.st_mode` is `0o100444` instead of what is checked
for which is `0o100400`. This is because basic Windows permissions
don't distinguish between user/group/all like Linux does. Note that
Windows Access Control Lists (ACLs) are not part of `stat` functionality.
- On Windows, `os.remove` will fail if a file is marked read-only. In
this case, need to mark it writable before deleting.

Signed-off-by: Sergey Kizunov <dfddabaa9af05982b01940b837a87844148069c9@ni.com>

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt