fix: use `tbl_deep_extend` now that user configuration is nested

[mehalter]

Now that the configuration table is nested the basic loop approach is not valid. It would require the user to supply the entire exclude = { filetypes = {}, buftypes = {} } to have a valid config. This utilizes the core neovim api for table merging which handles this

[brenoprata10]

Have you tested this extensively with the other configs? The last PR kinda broke the plugin. I would prefer splitting the exclude to exclude_bufftypes and exclude_filetypes instead

[mehalter]

Sure, I'm good with that! I'll let you run with it 😄