[FrameworkBundle][DX] Add --expand option to show full parameters.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | NA
| License       | MIT
| Doc PR        | TODO

Dumping non-scalar parameters most likely result to the output being a truncated JSON string. This PR simply adds an `--expand` flag which allows us to dump the full value of non-scalar parameters in YAML format (for maximum readability)

This only applies for the `txt` format. `xml`, `json`, and `md` will still have the truncated JSON representation.