Additionally, the IsDebugger and IsImmediateWindow properties have been removed from CompletionTriggerInfo. Any code that was checking these properties now checks for options that are set by the Controller in debugger scenarios.

A large change again, mostly mechanical. There's a fair amount to clean up and that will come in the next commit.

This change touches a lot of files but most of the changes are
mechanical. Essentially, this introduces a CompletionItemRules type as a
means to customize the behavior of a CompletionItem. This will
ultimately be the home of several methods that currently reside on
CompletionListProvider (such as IsCommitCharacter and
IsFilterCharacter), but only the SendEnterThroughToEditor method has
been moved in this change. Other methods will be moved in future
changes.

- Use suggestion mode by default in all debugger windows (not just in Immediate).
- Tweak completion to not send "Enter" through to single-line debugger windows (Watch, etc).  They don't support displaying more that one line of expression text.