fix writing task filename in generate-blueprint

[hide212131]

Example: In the 'server' sub-generator:

• Generated template file:

server
  templates
     template-file-server.ejs

• Code from 'generator.mjs':

files: [{ templates: ['template-file-base-application'] }],

---

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[hide212131]

I apologize for submitting the PR with an inappropriate username. I will fix it.

-> Done.