[Feat] Pin files to working set

Describe the problem

There should be a way to pin user specified files to the working set. Maybe by right clicking on a file and selecting pin file or with a pin button on each file item on hover. The pinned file should retain its relative positions across reboots.

Describe the solution you'd like

https://github.com/orgs/phcode-dev/discussions/2020

User requested feature.

Alternatives considered

No response

Additional context

No response