Add headers for NGENIX CDN

[elcanner]

Hi.
We have found that NGENIX CDN is not detecting for some files that was downloaded from CDN.

Code:

Use a CDN for all static assets: 32/100
...
FAILED - https://static1.car.ru/js_min/5b3a8e955aa958f111b55c6560ab4447_firebase_subscribe_v2.js
FAILED - https://static1.car.ru/img/external-icon.png
FAILED - https://static1.car.ru/i2/left-arr-picture.png
FAILED - https://static1.car.ru/i2/right-arr-picture.png
FAILED - https://static1.car.ru/c_min/678eb49e32eb5cadaea0d6571f0db351_pictures.css
...

Code:

~ dig static1.car.ru
...
static1.car.ru.        29    IN    A    212.193.152.59
static1.car.ru.        29    IN    A    37.220.161.35

~ whois 37.220.161.35
...
descr:          Network for NGENIX

~ dig static1.car.ru NS
...
car.ru.            299    IN    SOA    ns1.ngenix-dns.net

I think it's because of lack NGENIX headers in "cdn_headers" list in optimization_checks.py

https://github.com/WPO-Foundation/wptage...ks.py#L197

NGENIX CDN can be detected with "x-ngenix-cache" header.

Code:

~ curl -v -o /dev/null https://static1.car.ru/img/external-icon.png
...
< x-ngenix-cache: HIT

Can you please add this header ?

[pmeenan]

Should be fixed now: https://www.webpagetest.org/result/19052...cb3b43d36/