Smart selection mode

Is your feature request related to a problem? Please describe.

It would be nice if we could have "smart" selection mode, i.e., if the textobject takes up whole line/lines, use line-wise select, else use char-wise select. E.g., for the following lua function, use line-wise select:

local function my_func()
    return
end

But for this function, use char-wise select, as it does not take up a whole line at the beginning of the function:

local my_func = function()
    return
end

Describe the solution you'd like

Smartly detect if a textobj should have line-wise selection or char-wise selection based on its range.

Describe alternatives you've considered
N/A

Additional context
N/A

No file or test is named in the issue. Start by locating the textobject selection entry point and the code that computes its range; then compare the line-wise and character-wise selection behavior in the two Lua examples. Done means the selection mode is chosen from whether the range occupies whole lines, with both examples covered by tests.