Add 3 new labs

[david-a-wheeler]

Add labs for:

• Insecure Deserialization
• Debug and Assertion Code (specifically for assertions)
• Format Strings and Templates (specifically format strings)

With these additions we finally have all tier 0 and tier 1 labs as noted at https://best.openssf.org/labs. There are more labs we'd like to add, but the point is that we wanted to create the minimum set.

[david-a-wheeler]

All of these labs have PRs to add them to the Best Practices WG website, but don't merge this PR until the labs are posted :-).