Mainnet prep

[sisyphusSmiling]

Closes: #108

Description

• Adds Mainnet account to flow.json & README, removing Previewnet
• Adds Mainnet template contracts & configuration JSON-Cadence args
• Updates the deployment script to prevent USDCFlow TokenHandler configuration

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For contributor use:

• Targeted PR against main branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the standards mentioned here.
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.33%. Comparing base (a9d52f9) to head (ab4de5f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #111   +/-   ##
=======================================
  Coverage   86.33%   86.33%           
=======================================
  Files          17       17           
  Lines         922      922           
=======================================
  Hits          796      796           
  Misses        126      126           

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[joshuahannan]

Why is this commented out? Is this because we had to leave out the bridge related stuff in USDCFlow because it didn't migrate properly?

[sisyphusSmiling]

Yeah, since USDCFlow won't be migrated with bridge dependencies, we won't be able to configure a CadenceNativeTokenHandler for in the process of deploying the bridge contracts. We'll still be able to configure it before activating the bridge, it will just need to be done outside of the context of this script.