Pull core rust types into their own crate with WASM-compatible dependencies

[tkporter]

We want to be able to use some core types (like HyperlaneMessage, the Encode & Decode traits, etc) in WASM. This is because the Fuel indexer logic is WASM based (see hyperlane-xyz/fuel-contracts#39)

At the moment, HyperlaneMessage lives in hyperlane-core, which has a few dependencies that are not able to be compiled to WASM. These dependencies include ethers, I think tokio, and I'm sure many others. So for now in the Fuel indexer, we're just copying the Encode & Decode traits (https://github.com/hyperlane-xyz/fuel-contracts/pull/39/files#diff-9d5375e58ae555a71d183e064e25ded61d9e0e6da09c419a5243b312750f9a22), and the HyperlaneMessage type (https://github.com/hyperlane-xyz/fuel-contracts/pull/39/files#diff-c1df921b29777e810d4612bf6e315c71cf5f404d83cf0413cdeea3b4d2134ace). We'll soon be wanting access to the InterchainGasPayment struct too.

Ideally we shouldn't be copying code just to get it to work in WASM. Instead we should rip out some of the really basic types from hyperlane-core into something like a hyperlane-types crate that can compile to WASM, and then use that.

We should make sure that this crate is also able to be used in Sealevel / Solana for this PR #1345

[mattiekat]

Looking at this more closely I think instead of creating yet another crate, we should instead migrate a few things like the db module to hyperlane-base and then if anything remains that is not compatible, use feature flags as needed to create a "light" version of core.

hyperlane-core is already conceptually the "fundamental types" of hyperlane and hyperlane-base are the "fundamental tools for hyperlane operations" (e.g. agent lib).

Creating a third just muddies the already confusing division between core and base IMO.

At the end of the day though I think WASM support should not be too hard, I just need to read up on it a bit.