isolate types into a separate package

[stevejpurves]

Context

In some web contexts it is necessary to async load the thebe libraries in order to avoid incompatible dependencies coming in to the main build, however, when we include types from thebe-core in the consuming applications the dependencies are still added and can cause build time issues.

Proposal

create a thebe types package, which is dynamically built from thebe-core builds and published independently.

Tasks and updates

No response