cubicweb #5533285 Serve JS tests over http [validation pending]

Modern browsers no longer allow calling http:// URLs from a page served from a file:// URL.

prioritynormal
typebug
done in3.21.0
load1.000
load left0.000
closed by#22a89d0f4143 [devtools] Serve JS tests over HTTP (closes #5533285)
patch[devtools] Serve JS tests over HTTP [applied]