feat: strict inflation schedule

[mojtaba-esk]

Description

Part of #1570
Implement the strict inflation schedule specified in #1584

Remaining tasks

• implement inflation rate change based on block timestamp rather than block height
• set genesis time in x/mint state
• move MintDenom from param to x/mint state
• remove TestRandomizedGenState
• investigate why TestQueryGRPC / other integration tests are never run
• write a test that 1. starts a new chain, 2. verifies state of x/mint module for first few blocks, 3. skips ahead to a block one year later, 4. verifies inflation rate went down a bit
• remove Params entirely
• annual provisions for a year should be based on total supply at the beginning of that year
• for time-based inflation, calculate block provision as current block timestamp - previous block timestamp = seconds elapsed / seconds in a year * annual provisions for a year
• remove BlocksPerYear
• elaborate in README.md

FLUPs

• Add an invariant for the number of tokens minted per year #1755
• Add genesis_time to mint module's genesis state #1757
• Test time-based inflation #1758
• Implement a block height-based inflation mechanism #1756

[evan-forbes]

also, I think it should be relatively straightforward to write an integration test that measures the exact amount of inflation, and ensures the correct amount (to some level of precision) is being dished out to the pools/funds whatever. I also think we can get a little clever and make the TimeIota consensus parameter very large to force tendermint to add time that never passed to the header. That way, we can simulate time increasing waaaay faster than it actual does and not have to change any constants to watch the rate of inflation decrease/measure a year's worth of inflation.

[evan-forbes]

nice work!! ship ittttt

my only complaint is that we didn't get to an even 4200 lines, but I guess we can't get everything perfect

[cmwaters]

Nice work on this 👍

[cmwaters]

I have an alternative proposal to this which you can do in a follow up PR if you choose to. Rather than this, add a line in:

celestia-app/app/app.go

Lines 571 to 578 in 1e60076

	func (app *App) InitChainer(ctx sdk.Context, req abci.RequestInitChain) abci.ResponseInitChain {
	var genesisState GenesisState
	if err := tmjson.Unmarshal(req.AppStateBytes, &genesisState); err != nil {
	panic(err)
	}
	app.UpgradeKeeper.SetModuleVersionMap(ctx, app.mm.GetVersionMap())
	return app.mm.InitGenesis(ctx, app.appCodec, genesisState)
	}

Something like:

app.MintKeeper.SetGenesisTime(req.Time)

Which will set the genesis time. This also avoids the problem of PreviousBlockTime being nil at height 1

[evan-forbes]

githaaaaaaa

[evan-forbes]

for posterity, I asked @sweexordious to approve blindly since we've already approved and should start on any follow ups