fix: Expose registerMarkdownParser function instead of registering during the component lifecycle

[pawelgrimm]

Overview

In this PR, we are changing how we are setting up the AdaptiveCardRenderer. In the past, we would register the custom markdown parser in a useEffect. However, since the AdaptiveCards library only allows you to register a single markdown parser globally, it makes more sense to do so in the global scope instead of in a useEffect.

The main reason for this change is that in the initial render of AdaptiveCardRenderer, the markdown parser wasn't registered (because useEffect runs after the first render) and so markdown was not parsed and was rendered as plain text. This lead to a poor UX with UI Extensions in the first time a markdown-containing Adaptive Card response was rendered.

Test plan

• Follow test plan in https://github.com/Doist/todoist-web/pull/5382

[pawelgrimm]

@scottlovegrove I'd also appreciate your feedback since you have historical context.

[scottlovegrove]

Good spot on this fix 👍🏻 The changes make sense to me.

[rfgamaral]

Looks good to me 🚀 (sorry for the delay)