fix(difftool): fully resolve symlinks when comparing paths #36147
Fixes issue on mac where it was constantly reloading buffers as paths
were not being normalized and resolved correctly (in relation to buffer
name).
Quickfix entry:
/var/folders/pt/2s7dzyw12v36tsslrghfgpkr0000gn/T/git-difftool.m95lj8/right/app.vue
Buffer name:
/private/var/folders/pt/2s7dzyw12v36tsslrghfgpkr0000gn/T/git-difftool.m95lj8/right/app.vue
/var was synlinked to /private/var and this was not being properly
handled.
Also added lazy redraw to avoid too many redraws when this happens in
future and added test for symlink handling.
Signed-off-by: Tomas Slusny <slusnucky@gmail.com>