docs(converters): Add log warning messages indicating that converters will be deprecated in favor of those in MSstatsConvert

[tonywu1999]

Motivation and Context

In this PR, we copied all MSstats converters into MSstatsConvert to simplify the software architecture w.r.t. converters. On top of sending out an announcement to users on the MSstats mailing list, we should also log a warning message to users whenever they use converters from the MSstats package.

Changes

• Added a warning log message to every converter in MSstats that notifies users to migrate to MSstatsConvert by release 3.21

Testing

• Verified log message is printed on RStudio screen when using one of the converters

Checklist Before Requesting a Review

• I have read the MSstats contributing guidelines
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[mstaniak]

I would prefer it to be a message. Does R treat "WARN" option as a message? From the perspective of tryCatch() etc

[tonywu1999]

I would prefer it to be a message. Does R treat "WARN" option as a message? From the perspective of tryCatch() etc

Thanks for your input - I actually like message more too. I saw that the message command made the text red colored and more noticeable as well.

[devonjkohler]

This is a good addition to the log.

Looks all set to me.