Update tests for Dijkstra's algorithm to test both graph models

Use the already established macro pattern, move actual tests to a new file in src/testing.
Use the make_test_graph() function from the graph topology tests instead of duplicating it for the Dijkstra tests.

src/testing/graph_topology_testing.rs

@@ -1,4 +1,3 @@
-#[cfg(test)]
 #[macro_export]
 macro_rules! graph_topology_test_fixtures {
     ($T:ty) => {
@@ -90,7 +89,6 @@ macro_rules! graph_topology_test_fixtures {
     };
 }
 
-#[cfg(test)]
 #[macro_export]
 macro_rules! graph_topology_tests {
     ($T:ty) => {
@@ -702,7 +700,6 @@ macro_rules! graph_topology_tests {
     };
 }
 
-#[cfg(test)]
 #[macro_export]
 macro_rules! graph_topology_deletion_tests {
     ($T:ty) => {