Ensure common-utils rc snippets end with newlines

[trxcllnt]

Adds line endings to common-utils' rc snippets after #1095.

This ensures any features appending to these files after installing common-utils don't produce mangled files.

what happens now:

$ echo "export foo=bar" >> ~/.bashrc
$ tail -n1 ~/.bashrc
fiexport foo=bar

what used to/should happen:

$ echo "export foo=bar" >> ~/.bashrc
$ tail -n1 ~/.bashrc
export foo=bar

Maybe also a good idea to add the following vscode settings to the repo's devcontainer.json (and/or encourage contributors to use these settings?):

    "files.insertFinalNewline": true,
    "files.trimFinalNewlines": true,
    "files.trimTrailingWhitespace": true,

[samruddhikhandale]

Thanks for the quick fix!