Allow ctx.api calls inside .external

[KnightNiwrem]

Idea: Inside .external, skip the conversation's ctx.api transformer, effectively making it similar to bot.api calls that can be safely called inside .external.

[KnorpelSenf]

external can be called concurrently with regular API methods. How will you determine which API calls are executed from within external and which ones are executed concurrently from outside of it?