43 - Reusable variables using mustache

[nicomt]

• [x] Does all of your new or changed code have unit tests?
• [x] Is overall unit test statement coverage still above 85%?
• [x] Is code style linting passing with npm run lint?
• [x] Is the related GitHub issue number included in your branch name? ex branch name: fix/12-some-bug
• [x] Is the related GitHub issue number included in your pull request title? example PR title: "12 - Fixes some bug"
• [x] Is documentation still up to date after your change?

The documentation shows simple variable substitution (more advanced things can be done with mustache). This can be used in combination #46 to import variables from fragments in multiple test scenarios in the same folder

[nicomt]

@worldjoe Thanks for merging #46! (Sorry I missed the package-lock.json).

Related to this PR, I created this library for a project that I'm working on. It can be used to solve #43 too and it has some advantages over mustache like fallback defaults and simple escaping (in mustache escaping curly braces is really ugly).

command: echo "{{=<% %>=}}{{escapedCurly}}<%={{ }}=%>"

The new library seems to perform well in my tests but is obviously not battle-tested like mustache. If you're interested, I can write another PR using that library instead of mustache?

Anyway, I updated this PR, so it should be able to merge if you prefer this implementation

[worldjoe]

This is great.