What templating engine does Magento 2 use for it's Javascript widgets

### Is there an existing issue for this?

- [X] I have searched the existing issues

### What's missing?

- For example in the guide https://developer.adobe.com/commerce/frontend-core/javascript/jquery-widgets/breadcrumbs/#result
- Template `breadcrumbs.html`

```

<% _.each(breadcrumbs, function(crumb) { %>

• 
  <% if (crumb.link) { %>
  <%- crumb.label %>
  <% } else if (crumb.last) { %>
  <%= crumb.label %>
  <% } else { %>
  <%= crumb.label %>
  <% } %>
  

<% }); %>

```

What templating engine is this, where can we lookup the syntax documentation?

Start with the breadcrumbs.html example in the linked breadcrumbs guide and identify the templating engine represented by its syntax. Update the guide so readers can name the engine and find authoritative documentation for its syntax; the work is done when both the engine and syntax reference are clearly linked.

Written by the indexing model from the issue text.