Problem: The function visual_select() in treesitter/_select.lua is
executing `:normal! v<Esc>` to ensure that `gv` later goes
back to character Visual mode, but doing so when mode() is
already `v` first switches back to the Normal mode, then
executes <Esc>, which causes a beep.
Solution: Check if the mode() is already `v` and avoid any switching in
that case.
(cherry picked from commit 9afa8477b3)
2b37c26477
