distro: allow distro to specify a default locale

Currently the cloud-init default locale (en_US.UTF-8) is set by
the base datasource class.  This patch allows a distro to overide
the fallback value with one that's available in the distro but continues
to respect an image which has preconfigured a locale.

- Distro object now has a get_locale method which will return a
  preconfigure locale setting by checking the distros locale system
  configuration file.  If not set or not present, return the default
  locale of en_US.UTF-8 which retains behavior of all previous cloud-init
  releases.
- Apply locale now handles regenerating locales or system configuration
  files as needed.
- Adjust apply_locale logic to skip locale-regen if the specified LANG
  value is C.UTF-8,C, or POSIX; they do not require regeneration.
- Further add unittests to exercise the default paths for Ubuntu and
  non-ubuntu paths to validate they get the LANG expected.

0 files changed, 0 insertions, 0 deletions