Default implementations for Cw721Execute and Cw721Query

[taitruong]

Currently traits are implemented in cw721-base here:

https://github.com/CosmWasm/cw-nfts/blob/177a993dfb5a1a3164be1baf274f43b1ca53da53/contracts/cw721-base/src/execute.rs#L132

https://github.com/CosmWasm/cw-nfts/blob/177a993dfb5a1a3164be1baf274f43b1ca53da53/contracts/cw721-base/src/query.rs#L22

Any objection against moving this as default implementations traits in cw721 package? Here: https://github.com/CosmWasm/cw-nfts/blob/177a993dfb5a1a3164be1baf274f43b1ca53da53/packages/cw721/src/traits.rs#L18

[taitruong]

@shanev, @larry0x, let me know what you think about this.

Currently traits are implemented in cw721-base here:

https://github.com/CosmWasm/cw-nfts/blob/177a993dfb5a1a3164be1baf274f43b1ca53da53/contracts/cw721-base/src/execute.rs#L132

https://github.com/CosmWasm/cw-nfts/blob/177a993dfb5a1a3164be1baf274f43b1ca53da53/contracts/cw721-base/src/query.rs#L22

Any objection against moving this as default implementations traits in cw721 package? Here:

https://github.com/CosmWasm/cw-nfts/blob/177a993dfb5a1a3164be1baf274f43b1ca53da53/packages/cw721/src/traits.rs#L18

[taitruong]

Done in #161