Create shortcode for pulling in specific events and decommission the LF | Events block

[cjyabraham]

Since this isn't something that regular editors will need to use, I suggest we just stick with a shortcode, similar to the reports shortcode, instead of a Gutenberg block, as it requires less code and seems simpler to maintain etc.

• [x] Create shortcode for pulling in Events by free-text search and category
• [x] Add to the KCD page for pulling in KCD events
• [x] Swap it in instead of the LF | Events block on the Kubecon page (the only instance on the site)
• [x] Decommission the LF | Events block by removing the code

[cjyabraham]

deployed