Adds a launch_type model to track deploy target usage

What does this MR do?

Issue: #217707 (closed)

This MR adds a new model to keep track of what deploy target type a project is using, as described in this comment: https://gitlab.com/gitlab-org/telemetry/-/issues/382#note_342150277

Deploy Targets: https://about.gitlab.com/stages-devops-lifecycle/deploy-targets/

The purpose of this is primarily for instrumentation and so that we can answer questions like:

• What deploy targets are in use today?
• How many projects are using a given deploy target?

This MR is only concerned with creating the new model to store this data.

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides

Availability and Testing

As with an instrumentation to collect metrics on usage we should concern ourselves with performance impact. When adding metics you have to ask: Will this change affect CI/CD performance in any way? However this MR simply adds the model and it should therefore have no performance impacts.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.