ethers-ens ABI support

[jesus-eff]

How do folks feel about adding ABI support to ethers-ens? I think it would help my project out tremendously.

Rationale

I have 25 contracts and addresses I would like to register with ENS. I would also like to store ABIs for contracts in ENS. I am not aware of any scripts or UI that permit me to register ABIs with my ENS nodes. Therefore I've written two scripts, one to idempotently register sub nodes and ABIs and another to verify ABI records. These are rote tasks, anyone seeking to use ENS ABI features will have to do similar work. The lack of a formalized tool seems like an unnecessary barrier.

Implementation

ENS ABI contracts make use of two methods, ABI and setABI. Exposing these in ethers-ens would be very useful.

Lookup

https://github.com/ensdomains/ens-contracts/blob/master/contracts/resolvers/profiles/ABIResolver.sol#L35
ABI(bytes32, uint256) returns (uint256, bytes)
ethers-ens lookup-abi [--raw] --content-type=[string|int] [NAME|ADDRESS [...]]
Lookup an ABI entry, decoding the result to a string

• If the optional --raw flag is set, return the bytes stored, do not decode
• --content type can be a string of constant names or user provided integer value
  • ABI_JSON=1, ABI_ZLIB=2, ABI_CBOR=4, ABI_URI=8
• JSON, CBOR, and URI are strings
• zlib content type would have to be uncompressed
  * How can the tool differentiate between gzip, zip, and compress?

Set ABI

https://github.com/ensdomains/ens-contracts/blob/master/contracts/resolvers/profiles/ABIResolver.sol#L19
setABI(bytes32, uint256, bytes)
ethers-ens set-abi --compression-type=[gzip|zip|compress]] [--abi=[-|PATH|string]] --content-type=[string|int] NAME
Set the ABI for a node name

• If --content-type is ABI_JSON or ABI_ZLIB validate JSON input
• If --content-type is ABI_ZLIB compress --abi input
• If --content-type is ABI_ZLIB, require --compression-type