feat: re-implement event selector printing

[Bobface]

Motivation

#4455 implemented the printing of event selectors (the hash of the event signature, similar to function selectors). During the migration to Alloy, this seems to have been accidentally removed / replaced.

Solution

This PR re-implements the printing of event signatures.

Example

See Selector in the output below.

Welcome to Chisel! Type `!help` to show available commands.
➜ event SomeEvent(address addr);
➜ SomeEvent
Type: event
├ Name: SomeEvent(address addr)
├ Signature: "SomeEvent(address)"
└ Selector: 0x62e1088ac332ffa611ac64bd5a2aef2c27de42d3c61c686ec5c53753c35c7f68