plugins(websearch): support custom engine icons

[exscientiafortis]

this is useful as a visual cue for people who have more than two or three custom engines
could potentially include icons for the built-in engines but I think the tradeoff there is not so clear (not so likely people will have more than one or two of those, and we would have to bundle the icons)

[Kirottu]

I feel like if we are doing icon support, there should be some default icons. Probably just from OS icons since bundling our own would be messy on many levels.

[exscientiafortis]

My opinion: probably not worth worrying about icons for the four built-in engines. I would be surprised if a distro or desktop theme included icons for all four of them (I checked a couple, Google is sometimes included but not the others). It also adds overhead if someone later wants to add another built-in engine, because then we'd kind of need an icon for consistency. The effort and added maintainability overhead in making sure these work across everyone's environments outweighs the very limited benefit imo.

Plus, with this change, if a user really wants an icon for one of the built-in engines, they can just configure them as a Custom engine (what I did).

By supporting icons for the Custom engine we make it customizable without forcing anything on the user or adding any overhead to the project: it's purely opt-in and it's the user who is responsible for ensuring the icon is available in their environment

[Kirottu]

No I just figured we might as well have icons that we know the OS will have, like some generic search logos. But in general I agree allowing users to configure icons would be a good idea.

[exscientiafortis]

I see what you mean. Personally I think adding a generic icon to the existing built-in engines would not be worth the effort, because for me the value in the icon is the visual cue it gives for that specific engine when selecting from a bigger list.

The change as is has the advantage of being fully opt-in, it's purely an additional customization point for those who find value in it, adding no maintenance burden to the project nor affecting anyone's existing styling or config.

Would you consider adding this change as is, leaving the door open to revisiting the question of icons for built-in engines later if there's demand for it?