upgrades: perform a chain migration for #4084

[erwanor]

Is your feature request related to a problem? Please describe.
#4084 requires a migration upgrade in order to land on our testnet. The release of #4087 presents an opportunity to exercise that logic in more depth and generate information about reqs.

In order to do this without breaking functionality for clients, we will need to write a migration that moves all of the historical SwapExecutions from the JMT to NV storage.

• release: include upgrades: write a migration script for #4084 #4108 in the Testnet 70 release
• testnet: deploy Testnet 70, Deimos 6, The Upgrading #4087
• upgrades: confirm that private chain upgrade works with migration
• repo: merge dex: move SwapExecutions to NV storage #4107