Introduce the notion of "type summary options" as flags that can be passed...

Introduce the notion of "type summary options" as flags that can be passed down to individual summary formatters to alter their behavior in a formatter-dependent way
Two flags are introduced:
- preferred display language (as in, ObjC vs. C++)
- summary capping (as in, should a limit be put to the amount of data retrieved)

The meaning - if any - of these options is for individual formatters to establish
The topic of a subsequent commit will be to actually wire these through to individual data formatters

llvm-svn: 221482