Adopt new VM Service APIs to allow multiple clients to work with the debugger

See https://github.com/flutter/devtools/issues/1792
https://github.com/dart-lang/sdk/blob/master/pkg/dds/dds_protocol.md#requirepermissiontoresume

This will also require that we don't mess with another clients breakpoints:

https://github.com/flutter/devtools/issues/1792#issuecomment-1040609522