Generates an Anchor CPI crate from a JSON IDL.
In a new crate, write:
```rust
idl_macro::generate_cpi_crate!("src/idl.json");
declare_id!("GjphYQcbP1m3FuDyCTUJf2mUMxKPE3j6feWU1rxvC7Ps");
```
This will generate a fully functional Rust CPI client for your IDL.
Apache 2.0