Feature Request: Support custom / iTop-specific CI classes

[LexioJ]

Support custom / iTop-specific CI classes in CI search and rich previews

Problem

The iTop integration currently supports a fixed list of 11 CI classes:
PC, Phone, IPPhone, MobilePhone, Tablet, Printer, Peripheral,
PCSoftware, OtherSoftware, WebApplication, Software.

Every iTop deployment is different. Organizations routinely extend the CMDB
with custom subclasses of FunctionalCI — things like Monitor, Scanner,
NetworkDevice, VirtualMachine, StorageSystem, or domain-specific classes
created by iTop modules or in-house development.

With the current integration, CIs of those classes are completely invisible:

• They do not appear in smart-picker / reference search
• Pasting an iTop URL for one of them produces no rich preview in Talk or Deck
• There is no way for an administrator to enable them without modifying source code

Solution

Add an admin-configurable custom CI classes mechanism with the same
3-state control already used for built-in classes (Disable / Force Enable /
User Choice).

Admin workflow:

1. Open Admin Settings → iTop Integration → Custom CI Classes
2. Click "Browse iTop classes" — the integration queries the live iTop
   instance and returns any FunctionalCI subclasses not already covered by
   the built-in list
3. Tick the desired classes and save
4. The added classes immediately appear with a 3-state toggle and can be
   removed at any time

Under the hood:

• Custom classes are stored in custom_ci_classes (JSON) and merged with the
  standard list everywhere: effective class resolution, search, and reference
  resolution
• Search uses a safe name LIKE '%term%' OQL fallback so it works across any
  FunctionalCI subclass regardless of which fields it exposes
• Rich previews fall back to the generic FunctionalCI icon when no
  class-specific icon exists

Examples

Scenario	Before	After
Organisation has Monitor as a custom class	Not searchable; no preview	Admin enables it; users can search and get rich previews
MSP uses iTop module that adds ManagedDevice	Completely hidden	Admin adds it via the browser; appears in picker search
User pastes an iTop URL for a NetworkDevice CI into a Talk message	No card rendered	Rich link card appears (generic FunctionalCI icon)

Notes

• Validation prevents adding class names that conflict with built-in classes
  or contain unsafe characters
• Removing a custom class also cleans up any stale per-class state config
• No changes are needed by end-users; this is purely an admin-level extension
  of the existing configuration system