www/caddy: Add Caddy widgets for 24.7 new dashboard

[Monviech]

This PR is for discussion with @swhite2

Coming from the perspective of plugins, the widgets could be pluggable like this. What's left to solve is the translations, so this is like a proof of concept and has to be adjusted.

Screenshot (some domain details have been omitted with text editing):

What this adds:

1. A small widget called "CaddyDomain.js"

• that uses only existing API endpoints of Caddy to show a list of domains+port and their enabled status.
• The list in the widget is sorted by enabled status. Links are embedded to quickly get to the Caddy configuration pages.
• When Caddy is disabled, a warning will be shown with a link to the page where Caddy can be enabled.

2. A more complicated widget "CaddyCertificate.js" using a /new/ API endpoint that has not existed before.

• The new API endpoint uses openssl to read all certificates of Caddy from the filesystem. It uses "asyncio" for performance and a fast script execution time, even with many certificates
• The new "ttl_cache" is used in the actions to cache the result of the script to prevent repeated executions.
• The API endpoint is consumed by the CaddyCertificate widget, showing the validity status, hostname and localized datetime when it will expire in a neat list.
• Everything is async and fast.

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Since this is a WIP and POC it still needs some cleanup that will be done over time.

[swhite2]

To be honest, I like the usage of asyncio here, since openssl doesn't support parsing multiple paths concurrently.. Perhaps @AdSchellevis might have an opinion on this as well.