Make sure to exclude excel temporary files whose name starts with "~$".

[hidekoji]

Description

Changed searchAndReadExcelFiles to exclude Excel Temporary Files (whose file name starts with ~$)

Checklist

Make sure you have performed the following items before submitting this pull request. If not, please describe the reason.

• [ ] Add test cases for this fix/enhancement
• [ ] Pass devtools::check()
• [ ] Pass devtools::test()
• [ ] Test installing from github
• [x] Tested with Exploratory

[hidekoji]

This also includes fixes for:

• Exclude Exlce temporary files
• Support the "role" parameter for Snowflake