Add `MsgFundCommunityPool` to the Distribution Msgs

[fragwuerdig]

Having the MsgFundCommunityPool available from within smart contracts is a "hot" feature in Terra Classic. I hereby politely ask you to add this Msg to the list of valid wasmvm types. Changes include:

• added MsgFundCommunityPool to wasmvmtypes
• added serialization test
• will add corresponding PRs for wasmd and cosmwasm::std

See also the following issues:

• https://github.com/classic-terra/core/issues/288
• https://github.com/CosmWasm/cosmwasm/issues/1741

[webmaster128]

Merged in https://github.com/CosmWasm/wasmvm/pull/433. Thank you!