FormatNavigator has long stopped navigating anything - the generation of possible formatters matches is now done elsewhere
So, rename the class for what it truly is: a FormattersContainer
Also do a bunch of related text substitutions in the interest of overall naming clarity



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@197795 91177308-0d34-0410-b5e6-96231b3b80d8