Improve output verbosity in repometrics_data fn

[mpadge]

With default non-rlib verbosity, there are still a heap of pbapply progress bars (including one for each contributor), which then appear with no information at all.

• Maybe issue message at start that verbosity is by default off (unless explicitly set to "quiet")?
• Add progress bar for pkgstats analyses
• Add information on what the other progress bars are measuring, and maybe suppress those from repometrics_data_user(), when called from main function.