E2E: Add spec for vsa with custom template

What does this MR do and why?

• E2E spec for creating vsa using custom template
• Allow to pass custom css selectors to custom ui methods (there will be increased amount of cases where a lot of components reuse common ui components from gitlab-ui project)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.