Create api fuzzer CI template

Problem

Scanners run using a CI template that is included by the customer. API Fuzzer doesn't have a template which prevents usage of the scanner.

Proposal

Create a template similar to the other scanners.

• Scanner configuration via environment variables
• Support optional images provided by the user: worker, target
• Support testing external targets
• Verifies feature is enabled

The most relevant template to mimic would be

https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Security/DAST.gitlab-ci.yml

Tasks:

1. Support pre/post scripts
   1. FUZZAPI_D_PRE_SCRIPT - (optional) Pre script runs after docker login and docker network create, but before we start the scanning image container.
   2. FUZZAPI_D_POST_SCRIPT - (optional) Post script runs after scanning image container is started. This is the 1. [ ] Support target if provided (optional)
   3. FUZZAPI_D_TARGET_IMAGE
   4. FUZZAPI_D_TARGET_ENV
   5. FUZZAPI_D_TARGET_VOLUME
   6. FUZZAPI_D_TARGET_PORTS
2. Support worker if provided (optional)
   1. FUZZAPI_D_WORKER_IMAGE
   2. FUZZAPI_D_WORKER_ENV
   3. FUZZAPI_D_WORKER_VOLUME
   4. FUZZAPI_D_WORKER_PORTS
3. Set defaults when possible
4. Update features check for fuzzing
5. Misc docker
   1. FUZZAPI_D_NETWORK - (optional) Name of docker network, defaults to “testing-net” place to start your target(s) and kick off scanning if using our CLI tools.
6. Check into correct repo https://gitlab.com/gitlab-org/gitlab/-/tree/master/lib/gitlab/ci/templates/Security