Expose formula expression in api resource

src/ApiResource/Matchfunding/FormulaApiResource.php

@@ -19,4 +19,10 @@ class FormulaApiResource
 {
     #[API\ApiProperty(identifier: true, writable: false)]
     public string $name;
+
+    /**
+     * The underlying math expressed as a common-notation formula.
+     */
+    #[API\ApiProperty(writable: false)]
+    public string $expression;
 }

src/State/Matchfunding/FormulaStateProvider.php

@@ -41,6 +41,7 @@ class FormulaStateProvider implements ProviderInterface
     {
         $resource = new FormulaApiResource();
         $resource->name = $formula::getName();
+        $resource->expression = $formula::getAsExpression();
 
         return $resource;
     }