FR: flexible keymap support

[AbaoFromCUG]

Thanks for your amazing plugin!

I setup keymap Super-Tab which support snippet forward and select next via Tab, which means when I press Tab, will check snippet forward, select next in order, or fallback to normal key(Tab).

Here is my workaround of blink.cmp via hacking require("blink.cmp.keymap").apply_keymap_to_current_buffer. But I would like a official solution, like nvim-cmp

    local keymap = require("blink.cmp.keymap")
    local function apply_keymap_to_current_buffer()
        -- skip if we've already applied the keymaps
        for _, mapping in ipairs(vim.api.nvim_buf_get_keymap(0, "i")) do
            if mapping.desc == "blink.cmp" then
                return
            end
        end
        local insert_keys_to_commands = {
            ["<CR>"] = { "accept", "hide" },
            ["<C-Space>"] = { "show" },
            ["<C-d>"] = { "scroll_documentation_down" },
            ["<C-u>"] = { "scroll_documentation_up" },
            ["<Tab>"] = { "snippet_forward", "select_next" },
            ["<Down>"] = { "snippet_forward", "select_next" },
            ["<C-n>"] = { "snippet_forward", "select_next" },
            ["<S-Tab>"] = { "snippet_backward", "select_prev" },
            ["<Up>"] = { "snippet_backward", "select_prev" },
            ["<C-p>"] = { "snippet_backward", "select_prev" },
        }
        local snippet_keys_to_commands = {
            ["<Tab>"] = { "snippet_forward" },
            ["<Down>"] = { "snippet_forward" },
            ["<C-n>"] = { "snippet_forward" },
            ["<S-Tab>"] = { "snippet_backward" },
            ["<Up>"] = { "snippet_backward" },
            ["<C-p>"] = { "snippet_forward" },
        }

        -- insert mode: uses both snippet and insert commands
        for key, commands in pairs(insert_keys_to_commands) do
            keymap.set("i", key, function()
                for _, command in ipairs(commands) do
                    local did_run = require("blink.cmp")[command]()
                    if did_run then
                        return
                    end
                end
                return keymap.run_non_blink_keymap("i", key)
            end)
        end

        -- snippet mode
        for key, commands in pairs(snippet_keys_to_commands) do
            keymap.set("s", key, function()
                for _, command in ipairs(commands) do
                    local did_run = require("blink.cmp")[command]()
                    if did_run then
                        return
                    end
                end
                return keymap.run_non_blink_keymap("s", key)
            end)
        end
    end

    keymap.apply_keymap_to_current_buffer = apply_keymap_to_current_buffer