Add blockchain community option in the skill picker page

[sushilshinde]

Analysis and steps :

1. Identify blockchain program id, add in topcoder.constants.js
2. Decide the place of the blockchain community in the list (order)
3. Add necessarily related code in skill-picker.controller.js
4. Test whether blockchain is posted/get via API - memberCert/registrations

@ajefts please comment

[sushilshinde]

@ajefts I have committed these changes without 1 and 2 from the list above

Feature code is in skill-picker-blockchain#1241

[ajefts]

1. the group ID for this one is 20000010. Remember this is different than the other Communities that we have there since now we're using "groups" instead of legacy "events". So, joining this community will mean we add the member to the group via the group API (https://github.com/appirio-tech/tc1-api-core/blob/dev/tech.core/tech.core.service.identity/doc/swagger.yaml#L140). We have some examples of this in community-app, or you can also see example api calls in the postman examples: https://github.com/appirio-tech/tc1-api-core/blob/dev/tech.core/tech.core.service.identity/doc/groups-api.postman_collection.json#L626

2. Please place it under Cognitive.

[sushilshinde]

@ajefts thank you for the information, without that it was very hard to do what I did :)
Change is available at feature branch: skill-picker-blockchain#1241

One issue with Groups API

There is no API to get a single user subscription info from a group. Currently, I'm fetching all the users for a groupID via https://api.topcoder-dev.com/v3/groups/20000010/members/
And selecting one out of them, this is highly inefficient as users per group grows

Whereas in legacy case memberCerts/registrations has it
https://api.topcoder-dev.com/v3/memberCert/registrations/40153927/programs/3449/

[sushilshinde]

@ajefts done testing with new account, the code is at dev branch, it's ready for production.