[Feature] Only create the packages-install-path / dbt_packages folder if there are packages to install

[dbeatty10]

Is this your first time submitting a feature request?

• I have read the expectations for open source contributors
• I have searched the existing issues, and I could not find an existing issue for this feature
• I am requesting a straightforward extension of existing dbt functionality, rather than a Big Idea better suited to a discussion

Describe the feature

Even if you don't have a packages.yml file, dbt will create a dbt_packages folder whenever you run a dbt command.

Rather, it should only create this directory when running dbt deps (and only if there is at least one package to install).

Describe alternatives you've considered

It doesn't do much harm to have an empty dbt_packages, but it does feel like unnecessary cruft in the current working directory.

Who will this benefit?

No response

Are you interested in contributing this feature?

No response

Anything else?

See also: #6985

Here's an example of the extra folder in the dbt Cloud IDE: