[VarDumper] symfony.com color scheme on the CLI

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12355, #12391
| License       | MIT
| Doc PR        | -
Did you experiment the pb? Because I read that conemu supports 256 colors, so this 16 colors theme is not required