Add a way to ignore files from `bundle_dir()`

[colearendt]

bundle_dir() will currently include problematic things:

• files that are huge
• directories like packrat/, renv/, or venv/ that are known to be problematic

IIRC there is a .connectignore convention somewhere? We should look into that! And take note of what the internal tar implementation we are using has available.

[rsh52]

Hello @colearendt! What is the status on this, I'm running into an issue where I would like to ignore a sub-directory for a deployment and .rscignore doesn't work for wildcards in rsconnect.