[HOLD #16679] Refactor Header into a new component from MoneyRequestModal

[thienlnam]

#16679
In this PR we're updating IOUModal to MoneyRequestModal - I'm keeping the scope of those changes limited to push the PR forward as fast as possible - but it would be good to create a more generalized header component to refactor and clean up that code

#16679 (comment)

[thienlnam]

Actually going to do this in the same file