Project Wizard: sort interpreters by version within each runtime source group

Background

• The interpreters shown in the Python Environment Step and R Configuration Step are grouped by runtime source (e.g. Pyenv, System, Global, etc.), but not explicitly sorted by version within each group
• Generally, the dropdown list looks to be sorted as it seems interpreter discovery/registration occurs in some sort of alphabetical/numerical order
• However, it seems like sometimes the descending version order is not preserved, possibly because an interpreter gets saved as a "preferred interpreter" and its discovery and registration may be prioritized
  • Update: actually it sounds like there isn't really an order, so it may just happen to be that the runtimes start in version-order much of the time https://github.com/posit-dev/positron/issues/1044#issuecomment-1675099336
• We should apply a simple sort within each runtime source group to order them by version (descending, i.e. newest version towards the top)

Example from Project Wizard Python Environment Step

Relevant Code

• interpretersToDropdownItems in interpreterDropDownUtils.ts is where we'd need to add the sorting

Start in src/vs/workbench/browser/positronNewProjectWizard/utilities/interpreterDropDownUtils.ts at interpretersToDropdownItems. Trace how runtime source groups and interpreter versions are represented, then add the requested ordering within each group. Done means the Project Wizard Python and R interpreter dropdowns show newest versions first while preserving runtime source groups.