feat(venv): Make the venv linking strategy configurable

[arrdem]

Add a config_setting allowing users to toggle the default venv strategy so that users have to explicitly opt into the new-style static venv.

Mitigates #696

Changes are visible to end-users: yes

• Searched for relevant documentation and updated as needed: yes
• Breaking change (forces users to change their own code or config): yes
• Suggested release notes appear below: yes

Test plan

• Manual testing; please provide instructions so we can reproduce:

TODO