Define the roles of smart pointers for Qt

We want to define roles of smart pointers for Qt.

For the following smart pointers:

• weak
• shared
• scoped/unique

We need to answer the following questions:

• What is the definition
• When to use
• When do not use
• How to use

Acceptance criteria:

• Recommendations
• Best practices
• Definitions

Note: some of these question are already covered. Please consider the research in terms of API design.

Note: perhaps we could also create some stories to improve tools like clazy with new diagnostics.

The report is here (only for The Qt Company so far).