Add gitlab:graphql:analyze task

What does this MR do?

This adds a rake task that developers can use to assess the complexity cost of their queries.

Usage: (Manual QA)

bundle exec rake gitlab:graphql:analyze[path/to/query.graphql]

Example output:

$ be rake gitlab:graphql:analyze[app/assets/javascripts/error_tracking/queries/details.query.graphql]
app/assets/javascripts/error_tracking/queries/details.query.graphql
 - complexity: 23

Does this MR meet the acceptance criteria?

As a developer-facing tooling change, this does not require a changelog entry.

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

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