fix: issues Event derive macro on structs with unnamed fields

[PiquelChips]

Fix an issue where the Event derive macro would destructure structs with unnamed fields by creating variables named after ints (like "0"). Now, destructures to names with _ for the names to be acceptable by the compiler. To keep using the indexes in the format message, we append the the variables to the formatting, filtering out indeces that are not specified in the format message.

Setup removing subscribers from the event manager if their channel closes.

TODO

• if receive channel is closed, remove from list
• Setup tests for Events
  • make an event of every possible type (enum & struct with each field type)
  • annotate them fitting possible edge cases
• Fix macro for tests to pass