What does this PR do? ===================== This PR refactors param-input to use FormKit. FormKit is a structured form tool in the core. After the rewrite, we will be able to get semantic parameter error prompts, etc. meta link: https://meta.discourse.org/t/wishlist-param-dropdown-for-data-explorer-query/253883/28?u=lhc_fl
This commit updates the plugin to the latest guidelines, as shown in discourse-plugin-skeleton, which involves moving a lot of the code to dedicated files, use proper namespaces, use the autoloader as much as possible, etc.