Adapt generate-snippets-fixtures script for providers

[Wauplin]

cc @julien-c

Goal is to easily review inference snippets changes by generating and committing the expected snippets that will be shown on the Hub. For now mostly adapter for "hf-inference" provider + added 1 example with "replicate". In practice, we can add more examples once merged to #1129

How to use:

1. Go to @tasks-gen

2. Edit packages/tasks-gen/scripts/generate-snippets-fixtures.ts to add new examples

3. Run

pnpm run generate-snippets-fixtures

4. Use git diff to check difference => commit them

Afterwards, run tests (also done in CI)

pnpm test

Note: I haven't properly checked the snippets themselves. Will do it once merged when reviewing #1129.