fix: sanitize all secure keys in config

Check and remove all the secure keys in the site Mermaid Config,
not just `securityLevel`. Unfortunately, the logic of Mermaid's
`sanitize` function in `config.ts` is a bit convoluted. For instance,
the `secure` config restricts keys deeply in the object.

See: https://github.com/mermaid-js/mermaid/blob/9745f325cb9e1967640f0e85da193a2f820634f1/packages/mermaid/src/config.ts#L155-L190

tests/loadSite.spec.ts

@@ -83,7 +83,8 @@ test.describe('Site Loads', () => {
         config: `data:application/json,${encodeURIComponent(
           JSON.stringify({
             someOtherSetting: 'Test value',
-            securityLevel: 'loose'
+            securityLevel: 'loose',
+            secure: []
           })
         )}`
       }).toString()}`
@@ -99,6 +100,7 @@ test.describe('Site Loads', () => {
     });
     // should scrub unsafe securityLevel but keep other settings
     expect(parsedConfig.securityLevel).toBeUndefined();
+    expect(parsedConfig.secure).toBeUndefined();
   });
 
   test('should show troubleshooting steps if loading fails', async ({ editPage, page }) => {