feat(core): add Custom starter option to access preset flow

Adds a 'Custom' option to the starter selection that redirects to the original
preset-based flow, giving users access to more configuration options including:
- Framework selection
- Test runner choices
- Bundler options
- And other preset-specific configurations

When 'Custom' is selected, the flow returns 'skip' which triggers the preset
flow instead of the template flow.

Author: jaysoo

packages/create-nx-workspace/src/internal-utils/prompts.ts

@@ -147,6 +147,11 @@ export async function determineTemplate(
           message:
             'Angular           (fullstack monorepo with Angular and Express)',
         },
+        {
+          name: 'skip',
+          message:
+            'Custom            (more options for framework, test runners, etc.)',
+        },
       ],
       initial: 0,
     },