feat: replace template variables with values

Co-authored-by: Mythie <me@lucasjamessmith.me>

packages/lib/utils/render-custom-email-template.ts

@@ -0,0 +1,20 @@
+export const renderCustomEmailTemplate = <T extends Record<string, string>>(
+  template: string,
+  variables: T,
+): string => {
+  let t = template;
+
+  Object.entries(variables).forEach((entry) => {
+    const [key, value] = entry;
+
+    const placeholder = `{${key}}`;
+
+    const re = new RegExp(placeholder, 'g');
+
+    if (Object.prototype.hasOwnProperty.call(variables, key)) {
+      t = t.replace(re, String(value));
+    }
+  });
+
+  return t;
+};