Implement ability to send js challenge according custom rules

[EvgeniiMekhanik]

Currently if js challenge is enabled in our config we send js challenge to client on challengeble request (request with Accept header text/html). However, in CloudFare this is implemented differently. CloudFare allow the administrator to set up rules (which can be very defferent) according to which a challenge is sent to the client. It is a very good implementation, so we decide to implement the same ability in our config

[krizhanovsky]

We discussed in the chat that we should add a new ACTION for HTTPtables - jsch. I.e. we can write rules like

http_chain {
    hdr "accept" == '*; */*' -> jsch;
    mark == 1 -> jsch;

Please note that */* in the first rule can be in any place of the the value, so we might need something like '*/*', so we need #496 for this (there is no strict dependency, but we do need regexps for real work with HTTPtables).

Also please create a functional tests for this feature or a task for the tests.

This JSCH usage should be deployed on our website for CI

With the discussion #2025 (comment) need to add a best practice examples to the Wiki how to properly configure JSCH based on Accept header. E.g. see https://developers.cloudflare.com/waf/reference/cloudflare-challenges/

UPDATE this technique is known as soft-blocking, e.g. Cloudflare sends captcha for "suspicious" requests, e.g. by ASN, GeoIP or from Tor networks. The main use-case for JSCH is exactly soft-blocking.

[krizhanovsky]

#2131 is the appropriate PR. tempesta-tech/tempesta-test#626 is the testing issue and is the PR for this tempesta-tech/tempesta-test#627