Improve tab navigation with truncate filename set to false

There are 2 cases that can be improved.
* case 1
suppose I have three files, long_file_name_file_1, long_file_name_file_2, long_file_name_file_3. What I saw is
| empty_space |long_file_name_file_2| empty_space |

There is no way I can use mouse to move to the next buffer. I have to use `bnext/bprev` (also `BufferLinePick` not working as only one tab is shown)

* case 2
3 files, as above, but 2 of them are shown in bufferline tab
| long_file_name_file_1 | long_file_name_file_2|
What I expected is if I change focus to long_file_name_file_2, the tab should look like this:
| long_file_name_file_2 | long_file_name_file_3|
If I click on long_file_name_file_2, it should look like this:
| long_file_name_file_1 | long_file_name_file_2|
But it may not work as the spece left may less than length of long_file_name_file_1

Is it possible to show at least 2 tabs and the behaviour is this (suppose I have 5 files and 3 of them are shown)
| long_file... \| long_file_name_file_3 | long_file... |
If I click on `long_file... ` on the right, it will be
| long_file... \| long_file_name_file_4 | long_file... |
If I click on `long_file... ` on the left, it will be
| long_file... \| long_file_name_file_2 | long_file... |

_Originally posted by @ray-x in https://github.com/akinsho/bufferline.nvim/issues/533#issuecomment-1235409058_