Support Git Sparse Checkouts

Our Company uses a monorepo. All company code, including terraform, is in this repo. Because of this, the repo is quite large, and can take time to checkout / download. We’d love it if we could sparse checkout the terraform subdirectory since that’s all Spacelift needs. Maybe add it as a stack setting under source control.

Scenario:

An engineer needs to touch multiple stacks in their PR. That means they need to wait for all stacks to terraform plan before merging. Each stack has to pull their branch and run terraform… which means that every second we can shave off pulling their branch, the faster they can get feedback.