man.vim: Uniformly place cursor at the same column with `Ctrl-t` (#12608)

man.vim: Uniformly place cursor at the same column with `Ctrl-t` (#12608)

Functions col and cursor count each tab (0x9) as a byte, and
are complementary. On the other hand, the | command motion
takes into consideration how many screen columns a tab does
occupy and may move cursor to a column closer to the start
of line than col would report at that position.

The provided changes prefer the cursor function to the | command.

Co-authored-by: Aliaksei Budavei <0x000c70@gmail.com>