feat: make _resolvePath available in types

[Kr0san89]

The PR adds _resolvePath as protected in the typings so when extending the Filesystem class can be used

Acceptance Checklist

• Story: Code is focused on the linked stories and solves a problem
• One of:
  • For Bugs: A unit test is added or an existing one modified
  • For Features: New unit tests are added covering the new functions or modifications
• Code Documentation changes are included for public interfaces and important / complex additions
• External Documentation is included for API changes, or other external facing interfaces

Review Checklist

• The code does not duplicate existing functionality that exists elsewhere
• The code has been linted and follows team practices and style guidelines
• The changes in the PR are relevant to the title
  • changes not related should be moved to a different PR
• All errors or error handling is actionable, and informs the viewer on how to correct it

[Kr0san89]

@iamart can you have a look?