[Bug]: BufferLineCycleNext/Prev doesn't descend into closed groups

### Is there an existing issue for this?

- [X] I have searched the existing issues

### What happened?

`BufferLineCycleNext`/`Prev` only cycles between ungrouped buffers and open groups. Groups whose buffers are closed are not opened.

### What did you expect to happen?

`BufferLineCycleNext`/`Prev` should cycle through adjacent buffers regardless of whether their group is open or closed. If cycling into a group that's closed, the group should open, and close automatically upon leaving the group if `auto_close` is set to `true`.

### Config

I load `bufferline` with `lazy` and `require` the following module via the `config` parameter:

```lua
local keymap = vim.keymap.set
keymap("n", "bp", "BufferLineTogglePin", { noremap = true, silent = true, desc = "[P]in buffer" })
keymap("n", "bh", "BufferLineMovePrev", { noremap = true, silent = true, desc = "Move buffer left" })
keymap("n", "bl", "BufferLineMoveNext", { noremap = true, silent = true, desc = "Move buffer right" })
keymap("n", "", "BufferLineCyclePrev", { noremap = true, silent = true, desc = "Prev buffer" }) -- NOTE: doesn't seem to enter groups
keymap("n", "", "BufferLineCycleNext", { noremap = true, silent = true, desc = "Next buffer" }) -- NOTE: doesn't seem to enter groups

return function()
local groups = require("bufferline.groups").builtin
require("bufferline").setup(
{
options = {
diagnostics = "nvim_lsp",
diagnostics_indicator = function(count, level)
local icon = level:match("error") and " " or " "
return " " .. icon .. count
end,
groups = {
options = {
toggle_hidden_on_enter = true -- when you re-enter a hidden group this options re-opens that group so the buffer is visible
},
items = {
-- show pinned buffers first, then all ungrouped buffers, then docs then tests
groups.pinned:with({ icon = "󰐃 " }),
groups.ungrouped,
{
name = "Docs ",
highlight = { underline = true, sp = "#FC6F03" },
auto_close = true,
matcher = function(buf)
local filename = vim.api.nvim_buf_get_name(buf.id)
return filename:match("%.md") or filename:match("%.txt")
end,
},
{
name = "Tests ",
highlight = { underline = true, sp = "#036FFC" },
auto_close = true,
-- icon = " ",
matcher = function(buf)
local filename = vim.api.nvim_buf_get_name(buf.id)
return filename:match("%test_")
end,
},
},
},
color_icons = true,
highlights = {
tab_selected = {
bg = {
attribute = "fg",
highlight = "Pmenu",
},
},
},
indicator = { style = "underline" }, -- doesn't seem to be working
separator_style = { " ", " " },
},
}
)
end
```

### Additional Information

...

### commit

5cc447c