Running without debugging results in no service-extensions features

[DanTup]

Currently when running without debugging, we don't connect to Observatory at all. However, this means anything related to service extensions (like debug toggles) don't work (because we never see the service extensions load, and therefore never set the contexts).

This needs fixing - when running without debugging, we should do the same as debugging except for:

• Don't break on any exceptions
• Don't send any breakpoints

We may also wish to quit early out of evaluation, stack, variables requests if we're not sure that VS Code won't send them (it shouldn't, if we don't send a StoppedEvent?)