Support worktree development

[James-Mart]

Currently if I create a git worktree within psibase-contributor, there are several "gotchas" that confuse development.

1. If you want debugging support, you need to update the default .gdbinit at /root/
2. All the default .vscode/*.json files that are automatically created for you in the default workspace are not created in the worktree workspace, so you need to manually copy/rename them
3. Environment variables are still the same so running "psitest," "psinode," or "psibase" from the worktree can default to running the tools from the default workspace if they have already been built there
4. There is no docker volume mounted to /root/psibase.worktrees (the default worktree location), so rebuilding the container will wipe out worktrees.

Probably other issues as well. If worktrees are intended to be supported, it should be relatively simple to create and use one.