feat(feature-manager): remove spcp-myinfo from feature manager

[mantariksh]

Removes Singpass, Corppass and MyInfo functionality from feature manager.

Part of #1842

Breaking Changes

• Yes - this PR contains breaking changes
  • Details ...
• No - this PR is backwards compatible

Manual tests

• Create, activate and submit a Singpass form in email mode. Repeat for storage mode and decrypt the response.
• Create, activate and submit a Corppass form in email mode. Repeat for storage mode and decrypt the response.
• Create, activate and submit a MyInfo form in email mode

Tests

• Singpass, Corppass and MyInfo functionality in dev environment works as expected

Deploy Notes

Note that the server will now fail to start up without the necessary env vars for Singpass, Corppass and MyInfo functionality. Defaults for Mockpass have been added to docker-compose for the dev environment.