Make exported RNG functions respect changes to R's seed

[andrjohns]

Submission Checklist

• Run unit tests
• Declare copyright holder and agree to license (see below)

Summary

Exported RNG functions currently manage their state separately from R, so a user calling set.seed() has no effect on the result of the RNG.

This PR updates the exporting of RNG functions to additionally update their seed deterministically from the current seed in R

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):
Andrew Johnson

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)