tui: emit some termcodes later (after startup) (#7664)

For some reason, enabling focus reporting during terminal setup, causes
slow rendering during Nvim startup on tmux 2.3 with the tmux
`focus-events` option enabled.

To workaround that issue, this commit defers the request.

closes #7649

init.vim:
    call plug#begin('~/.config/nvim/plugged')
    Plug 'morhetz/gruvbox'
    call plug#end()
    set background=light " background light just to see the effect more quickly
    colorscheme gruvbox
.tmux.conf:
    set -g focus-events on
    set-option -ga terminal-overrides ",xterm-256color:Tc"
    set-option -g default-terminal "screen-256color"

Using `script` to record the terminal session (and `vterm-dump` to
post-process the result):

BEFORE this commit:
    ./build/bin/nvim -u NONE{CR}{LF}
    {DECSM 1049}{DECSM 1}{ESC =}
    {CUP *}{ED 2}{DECSM 2004}{DECSM 1004}{CSI 8,44,156 t}{CSI * r}
    {CUP 1,1}
    {CUP *}{ED 2}{DECSM 25}
    {DECRM 25}{CSI 2   q}{CSI 2   q}
    {CUP *}{ED 2}{LF}
    {ESC (B}{SGR *}{SGR 94}~                                                                                                                                                           {CR}{LF}
    ~                                                                                                                                                           {CR}{LF}

AFTER this commit:
    ./build/bin/nvim -u NONE{CR}{LF}
    {DECSM 1049}{DECSM 1}{ESC =}
    {CUP *}{ED 2}{CSI 8,44,156 t}{CSI * r}
    {CUP 1,1}
    {CUP *}{ED 2}{DECSM 2004}{DECSM 1004}{DECSM 25}
    {DECRM 25}{CSI 2   q}{CSI 2   q}
    {CUP *}{ED 2}{LF}
    {ESC (B}{SGR *}{SGR 94}~                                                                                                                                                           {CR}{LF}
    ~                                                                                                                                                           {CR}{LF}
    ...

0 files changed, 0 insertions, 0 deletions