[FASTIFY] Remove all koa reference inside the fastify package (source files and tests files)
### Is your feature request related to a problem? Please describe.

Related: https://github.com/tsedio/tsed/issues/932

### Describe the solution you'd like

Remove all Koa reference in the Fastify package.

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

### Acceptance criteria

- [ ] All base code is cleaned