Map Editor: highlight cursor

[x-Crown]

This PR introduces an additional hover highlight effect in the MTA:SA Editor. When the player hovers over an object in the map editor:

The object becomes semi-transparent.

A 3D animated bounding box is drawn around it with rainbow cycling colors (HSV → RGB).

The effect resets automatically when the cursor leaves the object

[omar-o22]

In my opinion, I don't think this would be good to have enabled by default.
Maybe it could be added as an option in the settings, with the default set to false.

[Fernando-A-Rocha]

The idea is cool. You should add a Map Editor setting to disable it.
Your code looks like it was generated by AI :-) Don't write unnecessary comments

[q8X]

it should use existing functions instead of creating a new one, this can be easily implemented through editor_main/client/main.lua, editor_main/client/gridlines.lua, also it's possible to support select/remove world object mode

[Lpsd]

If we're to implement something like this, it should be highly configurable - the user should be able to enable/disable it (disabled by default), choose opacity, line thickness, line color gradients (or solid color), etc.

[q8X]

i was going to implement this when this PR came out, but it seems like one of the recent changes to editor broke settings (kinda)

mtasa-resources/[editor]/editor_gui/client/options_backend.lua

Lines 133 to 137 in 604c05e

	-- check if the entries in the XML are valid, and remove invalid ones
	local validNodes = {}
	for _, nodeName in pairs(xmlVariants) do
	validNodes[nodeName] = true
	end

this issue could delete new settings if the mapper switches to outdated editor (which is likely going to happen when mappers switch between servers)