Use remarkable for Markdown formatting to support React Native

[opiation]

Contributes to #139

This PR uses the remarkable library to transform Markdown into HTML instead of marked. While marked is a competent library, it uses regular expressions to parse Markdown which include a syntax currently unsupported by the Hermes JS engine. In contrast, remarkable does use any regular expressions to parse so it seems to work just fine in React Native.

After switching to remarkable, using <FhirValue> in an Expo application to display Markdown content in HTML resulted in a new error. This turned to be a straightforward issue that the dompurify library cannot sanitize an HTML string with access to the DOM. Thus, this PR narrows HTML sanitizing to only be done when dompurify can do so.

How can I test this change?

Create a new Expo app using the bonfhir template for it. Add a <FhirValue> with some example Markdown content styled as HTML and validate that the HTML shows up literally on the Android screen.

const exampleMarkdown = "# Footer\n\nThis is a footer";

function ExampleScreen() {
  return <FhirValue
    options={{ style: "html" }}
    type="markdown"
    value={exampleMarkdown}
  />
}

The above should show something like:

<h1>Footer</h1>
<p>This is a footer</p>

Caveat

This helps make @bonfhir/core and @bonfhir/react more compatible with React Native configured with Hermes by addressing specific issues. Full Hermes compatibility is not confirmed yet however as testing the complete surface of Bonfhir libraries and APIs is out of scope of this fix. We welcome the community finding more compatibility issues however that we can prioritize and address as needed!

[opiation]

@julienblin, any objections to merging this? Is there any additional test you'd like me to run before merging this?

[lp]

💪

[opiation]

@julienblin, I'm merging this now. This change should be trivial to revert if it's revealed to be a problem.