We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
This moves all code comprehension-related code to a new library,
LibCodeComprehension.
This also moves some types related to code comprehension tasks (such as
autocomplete, find declaration) out of LibGUI and into
LibCodeComprehension.
This adds a new semantic token type, PreprocessorMacro.
Calls to preprocessor macros will now be highlighted when semantic
highlighting is enabled in Hack Studio.
