Add Twilio-WhatsApp adapter

[iMicknl]

Adapter is working fine with Twilio Sandbox.

Notes for reviewer:

• How should we do error handling in all adapters? I am trying to find the balance between throwing an error and just a console.warn, to prevent breaking bot flows.
• Should we change text formatting from <b>text</b> tot *text* for example. Or should this transformation be done in the bot code / middleware. Currently those default HTML to supported markdown transformations are built in.
• Not super Type strict since Twilio doesn't offer great typing for their package / API... More interfaces could be created in this package in the future.

TODO

• Add unit tests
• Check if oAuth support via Azure Bot Service is possible. [low-prio]

[iMicknl]

@szul please do not merge yet. I accidentally changed it to 'Ready for Review'.

I just updated my example and the library to the latest version of botbuilder and it looks like there was a breaking change in the definitions. (Or my example wasn't set up right. I need to dig in a bit more).

Argument of type '(context: TurnContext) => Promise<void>' is not assignable to parameter of type '(context: TurnContext) => Promise<any>'.
  Types of parameters 'context' and 'context' are incompatible.
  Types have separate declarations of a private property '_adapter'.

[iMicknl]

@szul It is ready for review. Could you have a look? I just need to write some unit tests before merge.

The issue of my previous post is resolved, thanks to @stevengum. Apparently my test project had different versions of botbuilder dependencies.

[szul]

@iMicknl That happened to me before: test directory node modules were out-of-sync with the base of the package ☹️

[szul]

When initially running the tests for this, I received the following error:

C:\Users\micha\x\botbuilder-community-js\libraries\botbuilder-adapter-twilio-whatsapp\lib\twilioWhatsAppAdapter.js:258
            activity.text = activity.text.replace(/<b>(.*?)<\/b>/gis, '*$1*');
                                                  ^

SyntaxError: Invalid regular expression flags

The syntax looked correct to me, and the flags were valid with the latest online documentation, so I checked my Node.JS version, which was in 8.x.x range. I upgraded to the latest Node.JS, and the tests then started running. Not sure if we need to make a note about Node.JS version support.

This is good to go. I left some minor version and language comments I think we should debate/change before merging.

[iMicknl]

@szul good catch! I didn't know the s expression flag is supported since > Node 8.. I am not sure which Node version we need to support? (and I think we should clearly state it somewhere in the documentation).