cmake: fix build failures on Windows and MSVC 2010

- Fixing -Wall, -g etc which are not supported by MSVC
- Let's link with the Qt's own copy of zlib (looks like Qt is by default
  configured to use a builtin copy on Windows)
- Do not show a console window on Windows
- Fix link failure related to std::wstring

Some coding style was unified by jkt.

Signed-off-by: Jan Kundrát <jkt@flaska.net>

BUG: 323310
Add support for asking SMTP password when sending email

MSA: AbstractMSA: Add signal passwordRequested() and slot setPassword() for requesting and setting password
MSA: SMTP: Use MSA passwordRequested() and setPassword() for requesting password before sending emails
Composer: Submission: Use MSA API for requesting and setting password, forward it to parent GUI widget
Gui: ComposeWidget: Use Gui::PasswordDialog for password requests from Composer

BUG: 320616
REVIEW: 112065