[FEATURE REQUEST] Don't ignore env vars setup in pre-install hooks #5265

Please confirm these before moving forward.

• I have searched for my feature proposal and have not found a work-in-progress/duplicate/resolved/discarded issue.
• This proposal is a completely new feature. If you want to suggest an improvement or an enhancement, please use this template.

Describe the new feature

If you set up pre-install environment variables like setx CARGO_HOME "C:\cargo" for the rustup winget package and proceed with the installations, the launched shell doesn't see this env var, my guess is because it inherits the env for the Uniget which was set before this pre-install was run.
Instead Uniget should update the environment and pass it to the newly spawned shell so that the process honors the pre-install hoooks that modify the environment

Describe how this new feature could help users

Would allow avoding the need to restart UniGetUI or reinstall the whole application after discovering it was installed to an incorrect location or something worse that depends on the environment being current