Rename project from redis-starter-rust to kafka-starter-rust

[jessevanassen]

Hello!

I noticed that the project name for the Rust based exercises used Redis instead of Kafka. This should fix that (although I don't know if any other tooling outside of the repo depends on the project name).

[andy1li]

@jessevanassen Thanks for the PR! Unfortunately it failed a test (rust).

I fixed it via #4. Here's our workflow if you're interested:

1. Only files in starter_templates need to be edited. (Other files will be generated in the second step.)
2. Generate (compile) other files using course-sdk:

course-sdk compile

3. Run course-sdk test (Well, my PR failed test (rust) too.)
4. The fix:
   a. cargo update
   b. course-sdk compile and course-sdk test more one time.