feat: Support for monorepo code management scenario

**Description of requested feature here**

Since dataform introduce team folders that will most likely ease monorepo scenario, it would be great to be able to support monorepo scenario defining root folder for dataform compilation.

**How does this help the users of the extension**

Monorepo for dataform can be pretty useful for standalone use cases provided as a monolitic code. Currently the extension cannot manage such scenarios.

The issue names no files, tests, or entry points. First clarify how a root folder should be configured for Dataform compilation and how monorepo projects are identified; done means the extension can manage the described monorepo scenario.

Written by the indexing model from the issue text.