* Features update logic for PPA in bionic

* node failing fixed after pnpm install from npm package manager

* for node version 16 pnpm version 7 is installed

* uninstalled pnpm package first and then reinstalled as per node version

* force installing pnpm package

* optimized logic to install compatible pnpm for node 16

* pnpm install specific version compatible for node

* new variable added pnpmVersion in node feature

* test case failure fixed

* fixed test cases

* fixing test cases

* pnpm version fixed for test cases

* default version for pnpm updated

* review comments addressed

* Update src/node/devcontainer-feature.json

---------
Co-authored-by: Samruddhi Khandale <samruddhikhandale@github.com>