Ensure public environments API is reliable and stable

[karrtikr]

Postmortem on Python API related bugs and causes

Each bug is listed into categories and marked if it could've been prevented with the stated precaution:

Bugs and potential precautionary measures

• resolveEnvironment returns undefined (only reproducible on Jupyter CI) #20147
  • [ ] Using public API internally
  • [ ] Adding unit tests for API surface
  • [x] Adding VSCode system tests
• Slow environments.known #20221
  • [x] Using public API internally
  • [ ] Adding unit tests for API surface
  • [ ] Adding VSCode system tests
• Newly created prefix conda environments are identified as named #20069
  • [ ] Using public API internally
  • [ ] Adding unit tests for API surface
  • [ ] Adding VSCode system tests
• resolved Environments have an invalid type for workspaceFolder, cannot be stored in memento #20104
  • [ ] Using public API internally
  • [ ] Adding unit tests for API surface
  • [x] Adding more internal tests
• resolved version for environments without python is incorrect, should be undefined instead #20110
  • [ ] Using public API internally
  • [x] Adding unit tests for API surface
• resolved name changes from undefined to empty string while discovering #20070
  • [x] Using public API internally
  • [x] Adding unit tests for API surface
• resolveEnvironment returns partial environment info from cache the first time (only the first session) #20147
  • [ ] Using public API internally
  • [ ] Adding unit tests for API surface
  • [x] Adding more internal tests

Expected behavior (required clarification or bug at Jupyter):

• API request for whether a refresh is going on: Misunderstanding on Jupyter's part #20188
• Envs returned via Python API contains envs from all workspaces #20068
• Workspace folder property contains path to env folder instead #20105
• Incorrect CLI args used to get activated conda enviornments #20071
• https://github.com/microsoft/vscode-python/issues/20220
• Python API triggers add events even after refresh promise has resolved #20216
• https://github.com/microsoft/vscode-python/issues/20239
• https://github.com/microsoft/vscode-python/issues/20300

Non reproducible:

• Jupyter claims sysprefix changes, not reproducible #20070

[karrtikr]

Discussed with team and here're the next steps:

• Use public API surface internally starting in the following order:
  • Interpreter quickpick UI
  • Components external to the interpreter component
  • Components external to the discovery component
• Move all logic from environmentApi.ts into the discovery component
  • Consolidate all Environment types into the external API type: Environment, so there's no need for conversion between types which is significant perf wise: https://github.com/microsoft/vscode-python/pull/23010
  • ...and more
• Fix testing holes where missing