Fix correctly display enums for function overload arguments

[NeOzay]

to achieve this bug requires function overloading and multiple variable assignment.

---@return string, number
---@overload fun(s: "test", a?:number):name:"name", string
function test() end

local name, aString = test("|") --- can see "test" and "name", only "test" is expected

using the debugger I go back to the findNearestSource function which does not see the correct source.
guide.eachSourceContain only returns the same source once, so you need to check if it is closer.

local function findNearestSource(state, position)
    ---@type parser.object
    local source
    guide.eachSourceContain(state.ast, position, function (src)
        if not source or source.start <= src.start then
            source = src
        end
    end)
    return source
end

[sumneko]

Thank you!