Currently, pyright does not support path variable expansion for tokens in the form of ${workspaceFolder:name}, which is documented by VSCode for multi-root workspaces. Following from the invitation at microsoft/pylance-release#4405 (comment), I added the feature. The current commit can be found at Seairth@37fff57.

Overall changes:

• Re-ordered the expandPathVariables arguments and added an additional argument for the list of workspaces
• Enhanced expandPathVariables to iterate over the workspaces and perform variable expansion for tokens in the form of ${workspaceFolder:name}
• Updated existing tests that used expandPathVariables
• Added new tests for expandPathVariables (including tests for existing functionality)

All tests pass. I have also built the VSCode extension and verified the new functionality.

Before I submit a PR, I want to make sure the commit meets "Contributing" requirements.