fix(dev): include document support for static page getPath functions.

[alextaing]

Fixes #415.

In the past, if users tried to access document fields in a static page getPath function, it would show up as "undefined" in the page URL. This PR addresses this by giving static pages access to the document object.

A couple changes were made to accommodate this functionality. We want to pass in a document in order correctly compute a getPath function. This means that when we iterate through templates to find the corresponding template document to our URL, (see findMatchingStaticTemplate), we need to retrieve the documents which is an asynchronous action. Therefore, the criterion function in findTemplateModuleInternal was changed to accept async functions.

For clarity, urlToFeature was also refactored. It was also found that defaultLocale was not being used in serverRenderRoute. Before, we hard-coded en to be the default Locale in urlToFeature. But in this refactor, we use defaultLocale instead.

J=SUMO-5417
TEST=manual

[mkilpatrick]

This is a "fix" vs a "feat". Can you update the commit message? Also mention "fixes [link to issue]" so it auto closes when this is merged.

Also does the document get injected during prod?

[alextaing]

This is a "fix" vs a "feat". Can you update the commit message? Also mention "fixes [link to issue]" so it auto closes when this is merged.

Also does the document get injected during prod?

Based on what I tested, when we create a getPath function that accesses the document object in a static page, then build and render the site using yext pages build, yext pages render, etc, the getPath functions correctly access the document fields. This led me to believe that the document also gets injected during this flow. Is this what you mean by prod, or is there another flow?

export const getPath: GetPath<ExternalImageData> = ({document}) => {
  return `${document.locale}.html`;
};