Fragment match export name

### Is your feature request related to a problem? Please describe.

Currently, we can't smoothly have fragment-matcher run with the other plugins like `typescript` etc, because fragement-matcher exports the possible types as `default`.

### Describe the solution you'd like

Ability to override the default export, or a setting that exports it with a specific name, like `export possibleTypes`

https://github.com/dotansimha/graphql-code-generator/blob/21fbf0db2ba7a560aeb0aa52e9b9bf792ac94227/packages/plugins/other/fragment-matcher/src/index.ts#L227

### Describe alternatives you've considered

For now I'm just importing it as default

### Is your feature request related to a problem? Please describe.

Combining fragment-matcher with other plugins isn't the best experience