refactor: redesign handler API

Move the handler definitions to a separate module and make the text
parsing a separate module. All handler logic operates on defined structs
instead now.

Author: dnaka91

Cargo.lock

@@ -25,7 +25,8 @@ twitch_api = { version = "0.7.0-rc.8", features = ["eventsub", "helix", "reqwest
 unidirs = "0.1.1"
 
 [dev-dependencies]
-pretty_assertions = "1.4.1"
+similar-asserts = "1.6.0"
+test-case = "3.3.1"
 
 [profile.release]
 lto = "thin"