FeatureInfo: Render Markdown into React components, add support for conditional rendering

[jacobwod]

Problem

The current implementation has two major flaws:

1. The markdown can not contain any [tags]. This is due to the shortcode feature in FeatureInfo that basically sees everything between [ and ] as a tag. This conflicts with Markdown's Links and Images syntax.
2. The resulting HTML is plain HTML, whereas we'd like to use MUI components on some ocassions. For example, a table should not parse into <table> but rather the MUI Table Component, to ensure correct rendering, dark mode support etc.

Suggestions

1. I will initially remove the shortcode functionality. We could look into making something similar, but it must not conflict with Markdown syntax.
2. I'll see if our Markdown parser can be extended to render MUI Components. A quick search gave this promising result. Update: using react-markdown makes this possible.
3. Implement some kind of conditional rendering. It could be used e.g not to render empty fields.

Currently implemented

• Fixed problem 1: Markdown can use all []-tags.
• Fixed problem 2: We return React components
• Added support for suggestion 3, see below.

Example of conditional rendering

<if {foo}>Will show if 'foo' is truthy</if>

<if {foo}=bar>Will show if 'foo' evaluates to 'bar'</if>

[jacobwod]

See https://github.com/hajkmap/Hajk/tree/feature/669-new-featureinfo

[jacobwod]

This is almost done, though it's been a while since I looked into this last time. AFAIR, everything works as expected, except the new DocumentHandler links, which need to be sent as Components.

For the purpose of documentation, can @sweco-seqtob show me an example of code for Infoclick box (in admin) that is needed in order to render a DocumentHandler link? (I finally got DocumentHandler running this week so I can set it up accordingly now.)