Create a wrapper function for sprintf to prevent potential fatal errors.

[imath]

This is a follow up of #8821

Create a "sanitization" function wrapping sprintf() to make sure expected placeholders are found into the translated strings.

Although we think this kind of function should be made available by WordPress, in ​this ticket the issue was diagnosed as invalid. It's probably ok when you have a lot of polyglots contributors like WordPress has, it's a different situation for plugins: let's prevent these potential fatals in 12.0