Fix skip_template & skip_secret_template options. Reorder manifest apply

[alexwilkerson]

This PR is to make the skip_template and skip_secret_template options functional. They currently do not work and still attempt to run when they are set to true.

The application order of the two manifest files was also changes so that the secret_template manifest is applied prior to the template manifest since the resources in the template manifest may need to use the secrets added by the secret_template.

Changes:

• Add check for when skip_template is set to true in the applyManifests function to skip the k8s manifest set in template. This will also skip dry runs
• Add check in applyManifests function to check if the template variable is empty prior to applying changes
• Add check for when skip_secret_template is set to true in the applyManifests function to skip the k8s manifest set in secret_template. This will also skip dry runs
• Add check in applyManifests function to check if the secret_template variable is empty prior to applying changes
• Reverse the order of k8s manifest applications so that the secret_template manifest is applied before the template manifest. This is a dependency issue where some of the k8s resources from the template manifest will need to have access to the secrets from the secret_template manifest
• Add test for skip_template: true
• Add test for skip_secret_template: true
• Add test for skip_template: true, skip_secret_template: true
• Add test for skip_template: true, dry_run: true
• Add test for skip_secret_template: true, dry_run: true
• Add test for skip_template: true, skip_secret_template: true, dry_run: true
• Update DOCS.md to be more explicit about above changes

If this is a change to the core functionality, did you make a corresponding PR to drone-eks?

• yes
• no
• n/a

Did you update the tests?

• yes
• no
• n/a

Did you update the docs?

• yes
• no
• n/a