Implement Parent Proposal for CCV and use created client to verify Handshake

[AdityaSripal]

Description

closes: #392

• Creates a proposal type and handling functions for creating a new child chain
• Upon passing the proposal, the IBC client for the child chain is created automatically
• The CCV channel on the parent chain for that child chain MUST be built on top of the above client.
• This ensures that the channel is speaking to the correct child chain and not an imposter

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• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[AdityaSripal]

Closed in favor of cosmos/interchain-security#5