Moved ingress template test classes from template_test.go to ingress_test.go

Problem to solve

As described in #140 (closed) we're trying to simplify the template tests as the file in question is quite large.

Proposed solution

Decompose template_test.go into individual test files for each template. Separate helper functions into a new file.

What does this MR do?

This MR moves the TestIngressTemplate_ test cases from template_test.go to its own file called ingress_test.go. Creates the assets/auto-deploy-app/test/templates directory and moves ingress_test.go to this path.