[ImgBot] Optimize images

*Total -- 87.04kb -> 61.05kb (29.86%)

/popup/assets/flag-en.png -- 11.32kb -> 5.30kb (53.21%)
/scripts/letItSnow.png -- 7.88kb -> 3.95kb (49.88%)
/popup/assets/flag-vi.png -- 5.81kb -> 3.34kb (42.46%)
/assets/icon128.png -- 7.35kb -> 5.01kb (31.87%)
/scripts/internet_archive.png -- 44.31kb -> 33.41kb (24.6%)
/assets/icon32.png -- 2.10kb -> 1.87kb (11%)
/scripts/fb_getPostReactionCount.jpg -- 8.27kb -> 8.17kb (1.24%)

Signed-off-by: ImgBotApp <ImgBotHelp@gmail.com>

Author: ImgBotApp