Refactor: tools: Remove output_filename from crm_mon.

This is only used by the HTML output. Instead, use the destination out
of pcmkoutput_t. This no longer needs to be passed to
print_html_status. Additionally, do not close the file handle. Let
pcmkoutput_free do that. Closing here will result in a segfault when
the finish function is called.

The resulting HTML file will have two HTML chunks in it - one chunk will
be everything currently being printed from the old code, and the second
chunk will only be what has been converted over to formatted output.