Remove action_pins.json and use dynamic SHA resolution

- Removed pkg/workflow/data/action_pins.json file
- Replaced embedded JSON with defaultActionVersions map
- Modified GetActionPin to use ActionResolver for dynamic SHA resolution
- Updated GetActionPinWithData to use only dynamic resolution
- Added data parameter to GetActionPin and GetActionPinByRepo
- Graceful fallback to version reference when resolver unavailable
- Updated all test files to work with new implementation
- All call sites updated to pass WorkflowData or nil

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Author: Copilot