1870567: Fix issue with locale and D-Bus method GetStatus; ENT-2772

[jirihnidek]

• BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1870567
• There were three reasons, why locale og GetStatus returned
  strings with wrong locale
  • REST API calls were called with wrong Accept-Language header,
    because the header was set for session and it was used for
    all REST API calls
  • Some strings (e.g. "Invalid") were translated during start
    of rhsm.service according system settings of locale and then
    these translated strings were used
  • Some strings are translated on candlepin server. Unfortunately
    some translated strings were saved in cache files and strings
    with unwanted translations were returned by GetStatus method
• So, some global variables with translated strings were moved
  to methods. Thus these strings are translated everytime, when
  method si called
• Caching of /var/lib/rhsm/cache/entitlement_status.json is
  disabled for rhsm.service to avoid returning strings with
  unwanted translation
• HTTP header with Accept-Language is set for every REST API call
• JSON document returned by GetStatus method was extended. So
  it includes now "status_id" and "reason_ids" with untranslated
  reasons. It can be used for checks in code.
• Modified and extended some unit tests

[jirihnidek]

Example how to test it:

[root@thinkpad-t580 subscription-manager]# busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Entitlement com.redhat.RHSM1.Entitlement GetStatus ss "" "fr_FR.UTF-8"
s "{\"status\": \"Invalide\", \"status_id\": \"invalid\", \"reasons\": {\"Fake OS Bits\": [\"Non pris en charge par un abonnement valide.\"], \"SP Server Bits\": [\"Non pris en charge par un abonnement valide.\"]}, \"reason_ids\": {\"38072\": [{\"key\": \"NOTCOVERED\", \"product_name\": \"Fake OS Bits\"}], \"99000\": [{\"key\": \"NOTCOVERED\", \"product_name\": \"SP Server Bits\"}]}, \"valid\": false}"
[root@thinkpad-t580 subscription-manager]# 
[root@thinkpad-t580 subscription-manager]# busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Entitlement com.redhat.RHSM1.Entitlement GetStatus ss "" "es_ES.UTF-8"
s "{\"status\": \"Inv\\u00e1lido\", \"status_id\": \"invalid\", \"reasons\": {\"SP Server Bits\": [\"No est\\u00e1 soportado por una suscripci\\u00f3n v\\u00e1lida\"], \"Fake OS Bits\": [\"No est\\u00e1 soportado por una suscripci\\u00f3n v\\u00e1lida\"]}, \"reason_ids\": {\"99000\": [{\"key\": \"NOTCOVERED\", \"product_name\": \"SP Server Bits\"}], \"38072\": [{\"key\": \"NOTCOVERED\", \"product_name\": \"Fake OS Bits\"}]}, \"valid\": false}"

[wottop]

buildbot: retest this please

[wottop]

Passed my functional tests. It needs automated tests to succeed and a squash.

[wottop]

final ack