Prop 458: Osmosis v15 Sodium Upgrade

This is a proposal to do a software upgrade to the v15.0.0 software tag of the Osmosis codebase on block height 8732500, which is estimated to occur on Thursday 16th March 16:00 UTC. Block times have high variance, so please monitor the chain for more precise time estimates.

# Upgrade Features
This upgrade adds the following features:

## Protorev module
The ProtoRev module developed by Skip, performs arbitrage transactions at the start of each block by identifying cyclic arbitrage, minting funds to perform it, burning the same amount of funds and returning the resultant profit into a module account controlled by Osmosis governance.

## Validator Set preferences module
The Validator Set preference module gives users and contracts a better UX for staking to a set of validators by allowing delegation to multiple validators in a custom ratio in a single transaction.

## Pool-manager module
The PoolManager module exists as a swap entry point for any pool model that exists on the chain by ensuring that all types of pools share the same underlying swap logic.

## IBC Improvements
Packet Forward Middleware
Adds the ability to route incoming IBC packets from a source chain to a destination chain.

Asynchronous Interchain Queries
Interchain Queries enable blockchains to query the state of an account on another chain without the need for ICA auth.

## Implemented Proposals
Minimum Gas Price
Authorised during Proposal 354, this adds a minimum gas price for all transactions across the Osmosis chain which is then distributed to delegators and validators.

IBC Rate Limits
Authorised during Proposal 427, initial IBC rate limits for large pools have been added, protecting assets on Osmosis in the event of security issues with Osmosis, a third party chain or IBC.

Stableswap pool conversion
Authorised during Proposal 441, pools 810 (stSTARS/STARS), 817 (stJUNO/JUNO) and 833 (stOSMO/OSMO) have been converted to Stableswap pools.

## Full Change Log

# Getting Prepared for the Upgrade
To build the binary, be sure to install golang 1.19.

As always, we recommend validators utilize 64GB of RAM. Since state migration is relatively negligible in this upgrade, it is likely possible to get away with less, but still not recommended. If you are unable to have 64GB of RAM, at a minimum have a total of 64GB of swap set to prevent out of memory errors.

If using cosmovisor, manually build & copy the osmosisd binary to /cosmovisor/upgrades/v15/bin/.

If not using cosmovisor, wait for your node to halt at the upgrade height, then install and run the v15.0.0 binary.

# Details of Upgrade Time
The proposal targets the upgrade proposal block to be 8732500, anticipated to be on Thursday 16th March 16:00 UTC. Note that block times have high variance, so keep monitoring the time. See countdown here.

The upgrade is anticipated to take approx 30 minutes, during which time, there will not be any on-chain activity on the network.

In the event of an issue at upgrade time, we should coordinate via the validators channel in discord to come to a quick emergency consensus and mitigate any further issues.