ABI embedding

[miraclx]

Based off #23.

Introduces the cargo near build subcommand with the --embed-abi flag.

Building without the --embed-abi flag is effectively analogous to the convention of using ./build.sh to build contracts.

With the flag however, cargo near inspects the contract, generating ABI that describes the contract and thereafter, embeds it into the contract. Which can be returned by calling the view method __contract_abi.

Some numbers (compiling the abi example in sdk):

• Without embedding ABI

  $ cargo near build --out-dir res --release
  $ wc -c < res/abi.wasm
  97313

• With embedded ABI

  $ cargo near build --out-dir res --release --embed-abi
  $ wc -c < res/abi.wasm
  99081

That's an increase of 1768 bytes (1.78% of the final binary).

Related: near/near-sdk-rs#893