typescript-axios: withSeparateModelsAndApi - fix missing import type

[m1k1o]

Fixes #17461.

Similar to #12195 but there does not seem to be solved type import issued for withSeparateModelsAndApi and as far as i saw, all the changes have already been addressed by #13964, therefore that PR can be closed.

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CC @TiFu (2017/07) @taxpon (2017/07) @sebastianhaas (2017/07) @kenisteward (2017/07) @Vrolijkx (2017/09) @macjohnny (2018/01) @topce (2018/10) @akehir (2019/07) @petejohansonxo (2019/11) @amakhrov (2020/02) @davidgamero (2022/03) @mkusaka (2022/04)