- replaces "move-only" terminology with "noncopyable"
- replaces compiler jargon like "guaranteed parameters"
and "lvalue" with corresponding language-level notions
- simplifies diagnostics about closures.
and probably more.
rdar://109281444
I enabled move-only types by default, but I didn't
realize that the `Feature::MoveOnly` needs to graduate
into a `LANGUAGE_FEATURE` so that `EvaluateIfConfigCondition`
will recognize `$MoveOnly` as being true.
fixes rdar://107050387
the main things still left behind the experimental flag(s) are
- move-only classes (guarded by MoveOnlyClasses feature)
- noimplicitcopy
- the _borrow operator
