Mainnet readiness: security

[cwgoes]

Objective:

• Ensure that the codebase (especially core protocol / state machine) has no bugs.
• Maximize defense-in-depth to contain any bugs which might slip through.
• Minimize the chances that an adversary can find an edge case which halts the chain.
• Minimize dependency security surface area.

Dependencies:

• Not panicking can cause consensus failure. #759
• Refactor transfer transaction creation and WASM to split shielded and transparent transfers #1677
• Audit the codebase for erroneous usage of architecture dependent types #826
• Audit codebase for all unwraps in transaction execution code #944
• Persisted db hashes may not match persisted data #1708
• dependencies clean-up #1562
• Cargo Udeps #1024
• Cargo Audit #1023
• The BlockHash field on state is not meaningful and not used. #2546
• Overall and throughput-based IBC rate limits #2552
• Audit for all usage of unchecked arithmetic and update nomenclature #2555
• Audit for all uses of HashSet in the codebase #2576
• 1-2 weeks of intensive internal red teaming with no finds

[brentstone]

Closing in favor of using the Project and Milestones