Pass targetPlatform in /{targetPlatform}/ instead ?targetPlatform=XXX to support proxied repositories with no query params available.

[rawlukMike]

I spend great deal of time trying to install latest version of python extension.
My (and many others according to similar #1135) organisation do not allow direct connection to marketplace.
Previously I could grab extension through Sonartype Nexus repository which was basically a proxy to marketplace.
The problem started when python extension ms-python team decided to include binary inside extension, which created multiple target platform packages.

I can download default one (alpinelinux) by creating link like:
https://nexus-name.organisation.com/repository/marketplace.visualstudio.com/_apis/public/gallery/publishers/ms-python/vsextensions/python/2025.0.0/vspackage
But this will only download alpine linux version. For windows I would need to add: ?targetPlatform=win32-x64 query, but nexus not support any params just link.

Moving targetPlatform into actual path instead query parameter would make marketplace more compliant with online proxied repositories.