Refactoring `external.py` (#2579)
* pass token & add typing
* updated docstring
* reorg
* improve docs
* test for private space
* changelog
* changed asserts
* pipelines
* streamline
* formatting
* int
* dataclass
* formatting
* annotations
* formatting
* external test fixes
* formatting
* typing
* addressing review
* fix tests
* dataframedata
* refactoring
* removed unused imports
* added better error message for invalid spaces
* removed unnecessary import
