governance: prevent scam proposals

[baktun14]

Akash has been a victim of scam proposals for a while now and there seems to be a solution implement by osmosis already.

https://twitter.com/sunnya97/status/1620058887578869763

Here's a reference implementation of Juno that will soon be released.

https://github.com/CosmosContracts/juno/blob/main/app/decorators/gov_filter.go

[andy108369]