Add kittest.toml config file (#7643)

* part of https://github.com/rerun-io/rerun/issues/10991

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Co-authored-by: lucasmerlin <8009393+lucasmerlin@users.noreply.github.com>

crates/egui_kittest/src/lib.rs

@@ -11,6 +11,7 @@ mod snapshot;
 pub use crate::snapshot::*;
 
 mod app_kind;
+mod config;
 mod node;
 mod renderer;
 #[cfg(feature = "wgpu")]