rearrange configuration to be closer to where it's consumed

src/generators.rs

@@ -1,9 +1,17 @@
-use crate::config::{EntryDeclaration, GeneratorDeclaration};
+use crate::config::EntryDeclaration;
 use crate::context::Context;
+use crate::generators::matrix::MatrixConfiguration;
+use serde::{Deserialize, Serialize};
 use std::rc::Rc;
 
 pub mod matrix;
 
+#[derive(Serialize, Deserialize, Default, Clone)]
+pub struct GeneratorDeclaration {
+    #[serde(default)]
+    pub matrix: Option<MatrixConfiguration>,
+}
+
 pub fn generate(
     context: Rc<Context>,
     generator: &GeneratorDeclaration,