This PR introduces these changes:

• Add a pre-commit hook to standardize EOF newlines
• Run pre-commit run --all-files end-of-file-fixer to standardize EOF newlines
• Resolve test failures caused by standardized EOF newlines

As can be seen in the changes, some files did not end with a newline, and other files contained more than one blank line at the end.

Merging this will allow pre-commit.ci to further enforce standards on new commits.