Expose all relevant types from @vue/apollo-composable

[nickmessing]

Is your feature request related to a problem? Please describe.
Some third-party libraries rely on types from vue-apollo, a good potential strategy would be to expose all types (probably renamed) from the root of the package:
Context: dreamonkey/graphql-codegen-stack#4

Describe the solution you'd like
Add type exports to project root.

Describe alternatives you've considered
Currently users have to import from the files directly, not optimal.

Additional context
Creating this task just to keep track of stuff to be done.