Universal formattable concept

[Alex2772]

Describe the need of your project

There's a zoo of formattable concepts in AUI:

• operator<< (default c++)
• fmt::formattable (from {fmt})
• PrintTo (from gtest)

They are not interchangeable. I want implement formattable/printable concept once per type instead implementing it 3x times per type.

Proposed solution

Take fmt::formattable as base formatting concept. As AUI uses both GTest and {fmt}, implement GTest's PrintTo function and use fmt::formattable there.

Alternatives you've considered

No response

Additional context

No response