Fix: Error when parse file using SimpleFileNodeParser and file's extension doesn't in FILE_NODE_PARSERS

[yukikwi]

Description

This PR is a patch for issue #13152 .
The problem is currently, if file extension is unsupported. It will add document to list of nodes that make code crash

Fixes # (issue)
#13152

New Package?

N/A

Version Bump?

N/A

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Added new unit/integration tests
• Added new notebook (that tests end-to-end)
• I stared at the code and made sure it makes sense

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added Google Colab support for the newly added notebooks.
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods

[yukikwi]

@logan-markewich I removed metadata check from unittest because code under SimpleFileNodeParser class doesn't add extra metadata to documents / nodes