deprecate legacy usage of `x/param` for param handling

[danwt]

In cosmos 47 params should now all be kept in module rather than in x/params

https://docs.cosmos.network/main/build/migrations/upgrading#xparams

Need to check we do it everywhere, and run a migration if not

Example cosmos/cosmos-sdk#12363

[mtsitrin]

we don't do it in most of our code base
it's backward compatibility, so not sure regarding the priority for this
we have all osmo and ethermint to migrate, and some of our modules

[danwt]

I see, it seems like it's only mandatory if upgrading to v50
closing for now

[mtsitrin]

• remove usage of x/param across the modules
• move the param store to be in keeper's store (instead of param subspace)
• review validation
• migration