[Feature] Add tests for installing local package when symlinks are not supported by the OS

[dbeatty10]

Housekeeping

• I am a maintainer of dbt-core

Short description

We are not currently testing the case where the user's operating system (OS) doesn't support symlinks. As a result, we could accidentally break these code paths in the future.

So we'd like to add functional tests for scenarios like #9719 specifically when the OS running dbt does not support symlinks.

Create a packages.yml file:

packages:
    - local: ../

Then install it:

dbt deps

Acceptance criteria

There are functional tests that cover the code paths when a user's operating system doesn't support symlinks (which is used for local package dependencies when running dbt deps).

Suggested Tests

We don't know how exactly to test it currently, so this would be something to brainstorm and choose an approach.

Impact to Other Teams

None.

Will backports be required?

It would probably be wise to backport to supported versions of dbt-core to avoid accidentally missing regressions when merging other backports!

Context

This was discovered during review of #9734.