Add new configuration option for #[solidity_interface] is attribute:
if($expr)
This expression will be executed during ERC165 supports_interface call,
and during normal call execution (but not during parsing), allowing to
conditionally disable some inherited interfaces based on contract data
Previously, generated `Call` enum had no documentation, and
documentation on interface items was only kept in generated solidity
interfaces.
Now all documentation will be moved from impl items to generated `Call`
enum