Enable luis reference in composer

[DingmaomaoBJTU]

Version

What version of the Emulator are you using.

Describe the bug

To support managed LU interruption scenario, luis reference support are needed:

## Interruptions
- [AcceptEventEntry intent](../Main/Main.lu#AcceptEventEntry)
- [ChangeCalendarEntry intent](../Main/Main.lu#ChangeCalendarEntry)
- [CheckAvailability intent](../Main/Main.lu#CheckAvailability)
- [ConnectToMeeting intent](../Main/Main.lu#ConnectToMeeting)
- [CreateCalendarEntry intent](../Main/Main.lu#CreateCalendarEntry)
- [DeleteCalendarEntry intent](../Main/Main.lu#DeleteCalendarEntry)
- [Time Remaining intent](../Main/Main.lu#TimeRemaining)

With current ludown, composer cannot recognize luis intent reference for now. Please ensure this scenario can be supported with bf-luis.

[boydc2014]

@DingmaomaoBJTU this would be enabled by 2 effort

1. we replace ludown with bf-luis Replace ludown with bf-luis #944
2. we use the new parser there supposed to be able to take a cusmoized import\resource resolve, so that we don't really depends very much to running the tool in certain folder.

[yochay]

FYI @vishwacsena

[vishwacsena]

Tagging with LU label.

Discussed this with @boydc2014 - the ignite solution is for composer to switch to using the bf-cli library for the LU parser. In the BF CLI,

• We are adding support for delegate based parsing. This will light up two scenarios:
  • General include references (like LG)
  • Cross training references (like this bug)
• We will add a suggestModel API that can do the required cross training

[hibrenda]

addressed in #1608