include_surrounding_whitespace should be an option on the mapping itself

Instead of requiring users to implement and write their own monolithic function themselves as in

keymaps = {
    ["af"] = "@function.outer",
    ["if"] = "@function.inner",
    ["aa"] = "@attribute.outer",
    ["ia"] = "@attribute.inner",
    ....
],
include_surrounding_whitespace = function (a)
    if a.query_string == "@function.outer" then
        return false
    elseif a.query_string == "@function.inner" then
        return false
    elseif a.query_string == "@attribute.outer" then
        return true
    elseif a.query_string == "@attribute.inner" then
        return false
    ....
end

I think making it an option on the keymap is a nicer and more expected API:

keymaps = {
    ["af"] = "@function.outer",
    ["if"] = "@function.inner",
    ["aa"] = { query = "@attribute.outer", includes_surrounding_whitespace = true },
    ["ia"] = "@attribute.inner",
    ....
],

Start by locating the keymaps configuration and the existing include_surrounding_whitespace handling in the textobjects plugin. Check how current mapping values are interpreted, then verify that per-keymap settings can express the requested behavior without breaking existing mappings.