hsts: add support for Strict-Transport-Security

- enable in the build (configure)
- header parsing
- host name lookup
- unit tests for the above
- CI build
- CURL_VERSION_HSTS bit
- curl_version_info support
- curl -V output
- curl-config --features
- CURLOPT_HSTS_CTRL
- man page for CURLOPT_HSTS_CTRL
- curl --hsts (sets CURLOPT_HSTS_CTRL and works with --libcurl)
- man page for --hsts
- save cache to disk
- load cache from disk
- CURLOPT_HSTS
- man page for CURLOPT_HSTS
- added docs/HSTS.md
- fixed --version docs
- adjusted curl_easy_duphandle

Closes #5896

src/tool_getparam.c

@@ -219,6 +219,7 @@ static const struct LongShort aliases[]= {
   {"A",  "user-agent",               ARG_STRING},
   {"b",  "cookie",                   ARG_STRING},
   {"ba", "alt-svc",                  ARG_STRING},
+  {"bb", "hsts",                     ARG_STRING},
   {"B",  "use-ascii",                ARG_BOOL},
   {"c",  "cookie-jar",               ARG_STRING},
   {"C",  "continue-at",              ARG_STRING},
@@ -1291,6 +1292,12 @@ ParameterError getparameter(const char *flag, /* f or -long-flag */
         else
           return PARAM_LIBCURL_DOESNT_SUPPORT;
         break;
+      case 'b': /* --hsts */
+        if(curlinfo->features & CURL_VERSION_HSTS)
+          GetStr(&config->hsts, nextarg);
+        else
+          return PARAM_LIBCURL_DOESNT_SUPPORT;
+        break;
       default:  /* --cookie string coming up: */
         if(nextarg[0] == '@') {
           nextarg++;