Explore alternative approaches to callr and import

[brshallo]

{funspotr} currently creates a new r instance before parsing each file:

This slows things down -- explore if you can use https://github.com/klmr/box/ to replace the {callr} and {import} steps which may offer some speed improvements and also may allow dropping current dependency on attach()

[brshallo]

Also look into backlit internals: https://github.com/r-lib/downlit

[brshallo]

Another useful package for installing missing dependencies may be attachment.