I265 training page revamp

Context: #265 (closed)

What's left:

• add the "Updated" date
• "Trainer's guide" links to the file, needs to link to the trainer's guide (if available)
• details page for each resource trainer's guide page for resources
• implement filtering (this is the hardest part)
• add the new component to the "Digital Safety Guides" page this page doesn't exist yet, but the new resources-list component has been turned into a reusable jinja macro, so it's ready to go when the page is created
• mobile friendly
• create a "sample slides" flowblock
• create the "join the tor community / training / resources ..." navbar