This pull request fixes a bug in presets and adds tests to ensure it
doesn't happen again.
Due to an oversight in refactoring, we returned extra and incorrect
parameters from other presets in the same template version when calling
`/templateversions/{templateversion}/presets`.
This pull request adds support for presets to coder provisioners.
If a template defines presets using a compatible version of the
provider, then this PR will allow those presets to be persisted to the
control plane database for use in workspace creation.