chore(r): Synchronize vendoring scripts with latest changes

[paleolimbot]

The updates to the Postgres and SQLite drivers were mostly good (thank you for doing them!)...these changes just iron out a few kinks:

• A few files weren't being ignored when building the driver during development
• The SQLite driver was still trying to copy sqlite3 from tools/. This existed on my computer and so it worked while packaging during release, but the tarball was over the 5 MB limit (CRAN pushed it through anyway) and we were both linking and vendoring sqlite3 in every installation. Because of this one we have a few notes on the package check page (but no message from CRAN yet): https://cran.r-project.org/web/checks/check_results_adbcsqlite.html

[lidavidm]

Ah, sorry about the missed changes. Thanks for fixing it!

[paleolimbot]

I will someday find a better system for making it less painful to refactor the upstream driver!