ENH: Fail early on missing files in MeshIO

Add a check on load if the file exists, if not fails with error Also removes "dicom" loading

PR Checklist

• No API changes were made (or the changes have been approved)
• No major design changes were made (or the changes have been approved)
• No new dependecies were added (or the new dependencies have been approved)
• Added test (or behavior not changed)
• Updated API documentation (or API not changed)
• Ran the CodeFormatEnforcer task and verified the header is in all new files
• Added iMSTK examples for all new major features (if any)

added Release 5.0 Topic: Geometry labels

requested review from @andrew.wilson

@andrew.wilson I haven't run all the examples against this there might be some paths where a missing file could get ignored, once we have all the merges in we will run all the examples and any issues with those should come up

resolved all threads

mentioned in commit ce67a549

merged