Provide option to stop, warn or log when pull/checkout fails

[vedhav]

Closes #9

Changes:
The load_pkgs now checks for the status of the pull/checkout and log this for the user.
The user can choose if they need an error, warning, or message logged when git failure occurs. The default is warning.
This can also be set using an option in their .Rprofile using:

options('multiloadr.load.verbose' = 'error') # stop with an error
options('multiloadr.load.verbose' = 'warning') # show a warning => default
options('multiloadr.load.verbose' = 'message') # show a message

[vedhav]

Hey @donyunardi
Looks like the CI failed because there was an error installing httpuv and shiny in the Install dependencies step. I triggered the check by creating a PR on the fork and it was successful. However, I think we can use ubuntu-latest ubuntu-20.04 (the release version of ubuntu does not seem to install R release version properly) instead of macos-latest for the CI along with R release instead of 4.2.2.

[vedhav]

Hopefully, you like the CI changes I proposed I was able to implement them (after a few tries as always 😆). I checked the CI on the fork and it seems to work now, runs faster too 😉

[donyunardi]

Thanks so much for these improvements, @vedhav!
Just had small changes.
If you don't have time, I'd be more than happy to make the changes.

[donyunardi]

Hopefully, you like the CI changes I proposed I

I do! Thank you!

[donyunardi]

LGTM!