Set filetype for TOC window

[lambtho12]

Is your feature request related to a problem? Please describe it.
The current TOC window has no filetype. Defining a filetype for would allow other plugins to detect it and act accordingly.
In specific, the akinsho/bufferline plugin can offset the bufferline (tagline) for vertical windows such as a treeview, etc. This offset works by detecting the filetype of the opened window.

Describe the solution you'd like
Set filetype=vimtex-toc or something like that for this window by default. I don't think this would cause any issue, especially considering that no filetype is currently set.

[lervag]

I don't see a problem with this request. I've added this now, please test and let me know if it works as expected for you.

[lambtho12]

Awesome! It works as expected.
Thank you very much for your quick response and for this amazing plugin!

[lervag]

Great! Thanks for the kind words :)