connections.cgi: Modernize connection WUI with refresh interval, zone filtering and...

connections.cgi: Modernize connection WUI with refresh interval, zone filtering and search function

- Implement AJAX-based dynamic table updates
- Add configurable auto-refresh (2-60 seconds or disabled)
- Introduce toggleable search/filter panel for:
  * IP addresses (source/destination)
  * Port numbers
  * Protocol types
- Add zone-based filtering (GREEN/BLUE/ORANGE/VPN etc.)
- Display active filters and connection count
- Maintain existing network zone coloring system
- Improve error handling and user feedback
- Use jQuery for AJAX requests and DOM manipulation

get_table.cgi: Add JSON API for connection data

- New backend providing filtered connection data
- Supports all filtering from connections.cgi:
  * Network zones
  * IP addresses
  * Port numbers
  * Protocols
- Returns structured data including:
  * Colored IPs by zone
  * Port numbers
  * Connection states
  * TTL values
  * Traffic counters
  * Country flags
- Uses JSON::PP for efficient encoding
- Handles conntrack data processing

Langs needs to be updated with an update-lang-cache.

Fixes:

10.05.2025
- Removed deprecated `Switch` module
- Add more code comments
- Optimize code structure by adjusting indentation
- Cleared code which was not used
- Fix typo in toggle selector

25.05.2025
- Added source and destination NAT again into table
- Updated also language files for new Core version 195

Signed-off-by: ummeegge <ummeegge@ipfire.org>