TS-2691 Fix how we count redirect retries

TS-2691 Also eliminate api_enable_redirection which seems superfluous
TS-2690 Fixes for escalation plugin

This fixes the following:

1. Change to use the API for following redirects.
2. Make it only replace the "host" portions of a URL
3. Cleanup.
TS-2693 Modify string ownership for TSRedirectUrlSet()
TS-2692 Add an API to Get the current redirection retry count
TS-2707 Migrate TSRedirectUrlSet/Get to TSHttpTxnRedirectUrlSet/Get

1. We leave TSRedirectUrlSet() / Get() as is (as far as functionality
goes). This makes this proposal both API and binary compatible with v4.2.x.

2. We mark them as Deprecated, removing the old API in 6.0.0.

3. We add TSHttpTxnRedirectSet() / Get() , with the new string ownership as
described above. This naming convention is much better aligned with the rest
of our APIs.

I left the URL string lengths as int type for now, we’ll discuss at the Summit
about TS-2514, changing our usage of “int” to more appropriate size_t etc.
TS-2690 Make the escalate plugin support URL and Host redirects

TS-2690 Support multiple status codes for each rule, e.g. 403,404:
TS-2703 Add a text log format to escalate plugin