Add issue generation script

[kolkhis]

I wanted to take the manual labor out of creating 4 issues for each unit.
This uses the gh command line tool to create issues on the repo, and reads from files in .github/ISSUE_TEMPLATES for the body of the issues.

The GH CLI tool must be configured on your local system with gh auth login, and the access token you use must have the correct permissions to create issues for the org.

Follows the same format that has been used all through lac and psc so far.

Ex: Create a worksheet issue for unit 5

cd ./scripts
./create-issues -u 5 -t worksheet

repeat with -t intro, -t lab, -t bonus.

Limitation is that you cannot specify "Type" via the gh tool so that will need to be manually added.

[kolkhis]

An example loop to create all 4 issues for an entire unit:

cd ./scripts
for type in intro lab worksheet bonus; do ./create-issues --unit 5 --type $type; done

[cmckee786]

Wow, cool stuff here, will have to take some notes on this