Replace dependency on Indy SDK with Indy VDR

[esplinr]

Indy-VDR is receiving more development than Indy-SDK, so we should replace calls to libindy with calls to indy-vdr.

Steps:

• Update unit tests.
• Update integration tests.
• Update package dependencies.

Notes:

• Related issue in Indy Node.

[WadeBarnes]

This needs to be done in conjunction with, or before, hyperledger/indy-node#1644.

hyperledger/indy-test-automation#125 can be used as a reference for this migration.

[burdettadam]

I am happy to work on this task.

[burdettadam]

Feel free to track my progress in this draft pr, #1711

[burdettadam]

Progress is being made on #1716