tools: improve cluster summary display in crm_mon

• Refactor to use same functions for HTML/XML/console output to encourage consistency
• Console output now prints last updated/changed headers on one line and node/resource counts on one line to conserve space
• XML output now always shows all headers, ignoring --quiet and --hide-headers
• XML output now prints the same cluster options as HTML
• HTML output now respects the --quiet and --hide-headers options
• HTML output now prints last changed time and stack if requested
• HTML output now prints DC version and quorum status if printing DC
• HTML output now prints DC if none, even if DC was not requested