feat: add a Cloud Bigtable fraud-detection terraform code

[ikettaneh]

This is the first PR out of three PRs that introduce Cloud Bigtable fraud-detection use-case example.

This PR adds the following:

1. The Terraform code that builds and destroys the infrastructure.
2. An already-trained ML model that detects credit card fraudulent transactions.
3. The datasets used for training the ML model.
4. A simple Java test that builds the infrastructure.

Future PRs will introduce the Dataflow jobs for preloading Cloud Bigtable and running the streaming fraud-detection pipeline.

Fixes #issue

It's a good idea to open an issue first for discussion.

• [x] I have followed Sample Format Guide
• [ ] pom.xml parent set to latest shared-configuration
• [x] Appropriate changes to README are included in PR
• [ ] API's need to be enabled to test (tell us)
• [ ] Environment Variables need to be set (ask us to set them)
• [x] Tests pass: mvn clean verify required
• [x] Lint passes: mvn -P lint checkstyle:check required
• [ ] Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only
• [ ] Please merge this PR for me once it is approved.

[billyjacobson]

Thanks for the review @alicejli, with regards to the new directory, this is a larger sample application, so it made sense to group it all together separately to be easier to maintain, manage and understand for customers reading through the code example.

[ikettaneh]

Thank you @alicejli for your review. I have addressed your comments