lower permissions file with mnemonic on windows

[qrayven]

Description

Windows has a much different permission model than POSIX, (UNIX).
Files containing the mnemonic should have been saved by CLI with permissions similar to 600 on the UNIX system.

#611 (comment)

Motivation

Its a good security practice to use a layered security model

Requirements

Write a list of what you want this feature to do.

1. the ile containing a mnemonic shouldn't be read by other users or groups of users than the user that starts the process

Open questions (optional)

what is the secure equivalence of 0600 on Windows?

Are you planning to do it yourself in a pull request?

Yes/No.

[thibault-martinez]

Closed by #1281