Improve use_metadata() messaging

[daxkellie]

It's not totally clear what use_metadata() does once it is run in the console. Some cli_progress_step messages would help the user understand what it does and where to look next

As a sidenote, it might be worth considering whether this function needs a more specific name? For example, is the current functionality more suggestive of use_metadata_template()? (like usethis::use_rmarkdown_template()). Would it be possible to use a non-template file? Would there be a function for that?

[daxkellie]

Updated use_metadata() messages in commits 1c4daa7 and 65ba6e5