feat: added WASM functions & mm test

[mickvandijke]

Adds all the necessary WASM bindings for the webapp to be able to upload private data to a vault and fetch it again.

Also includes a test that puts private data to a vault and pays for the records using MetaMask.

Running the MetaMask example:

1. Make sure that you have MetaMask installed in your browser.
2. Run a local network with websockets enabled.
3. Depending on the EVM network you are using for the test, make sure that the network has been added to MetaMask and that you have some gas and payment tokens in your account. (I can send some for Arb Sepolia or Arb One)
4. Build the WASM pkg using the correct EVM network (don't use the local setting here, you need to define the RPC_URL etc manually as ENV vars if you want to use a local EVM network):

Using Arbitrum Sepolia for this example.

RPC_URL="https://sepolia-rollup.arbitrum.io/rpc" PAYMENT_TOKEN_ADDRESS="0xBE1802c27C324a28aeBcd7eeC7D734246C807194" DATA_PAYMENTS_ADDRESS="0xDd56b03Dae2Ab8594D80269EC4518D13F1A110BD" wasm-pack build --release --target=web autonomi --features=data,vault,external-signer

5. Start a webserver using Python for example:

Run this command inside the safe_network repo.

python3 -m http.server 8000 -d autonomi

6. Visit http://localhost:8000/examples/metamask/
7. Make sure that you have the right network selected in MetaMask!
8. Enter a ws multiaddr of a local node and press run.

[grumbach]

LGMT