web-wallet: Change password setting as enabled by default

[HDauven]

Resolves #3287

[nortonandreev]

If so, let's update this saying that Setting a password is recommended.
Update the copy to something that explains why setting a password is more secure rather than using the mnemonic – as this is the opposite of what the current copy suggests.

If the user disables the Password option, we can display a warning banner instead, outlining the risks of not setting a password.

[nortonandreev]

I think we can get rid of the Please store your password safely. paragraph.

also, check if you want to enforce the minimum length of 8 characters, or ditch any requirements, as Thomas suggested.

I would still consult with @ZER0 first, as there has been quite a lot of discussions around this flow and personally don't want to proceed unless we hear from him too.