refactor(bot): introduce response type

The response type holds represents the way a bot can respond to a
message it executes and allows us to move the IRC dependency out of
bot and into only the main module.

build.zig

@@ -152,12 +152,7 @@ pub fn build(b: *std.Build) !void {
         })),
 
         // Our bot tests needs zircon module import,
-        try testRunWithImports(b, target, "bot", &.{
-            .{
-                .name = "zircon",
-                .module = zircon.module("zircon"),
-            },
-        }),
+        try testRun(b, target, "bot"),
         // Our module tests for each module we want to add. If
         // breaking out new functionality to a module, remember to
         // bump the length of the array above.