Refactor Country / Language Context: Introduce Locale Context, add Redirector Adapter

[Stefan Hagspiel]

Locale Adapter

• remove language_adapter and country_adapter context, introduce locale_adapter
• remove default_language and default_country setting, introduce default_locale

Redirector Adapter

Implement redirector_adapter which allows to define redirect decisions in a more granular way.
Redirector can be enabled (default) or disabled.

i18n
    registry:
        redirector:
            cookie:
                enabled: false

Available Redirectors

• cookie redirector (prio 300): If enabled user gets redirected to selected language.
• geo redirector (prio 200): If enabled user gets redirected based on IP and browser language
• fallback redirector (prio 100): If enabled user gets redirected based on i18n default_locale setting (per zone) or default locale defined in pimcore settings.