added script to convert urdfs/meshes to instanceable USD in batches

[hapatel-bdai]

Description

Adding a script that converts URDFs and Meshes to instanceable formatted usd in batch (recursively searching dir) so that users do not have to do it one at a time

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[jsmith-bdai]

LGTM (already reviewed on internal repo)