[rac] Download all rules for a country code in libaddressinput.

[rac] Download all rules for a country code in libaddressinput.

This patch enables downloading all rules for a country code. The rules are
organized into a Ruleset tree, where nodes contain region-wide rules,
language-specific rules, and Rulesets for the sub-regions.

For example, the country code of Canada is "CA". The Ruleset for "CA"
contains the general validation rules for Canada in the default language
of the country, which is English, or "en".

One of the child nodes of "CA" is a Rule for "fr" language. This Rule
contains the general validation rules for Canada in the French language.

The rest of the child nodes of "CA" are the Ruleset objects for all of the
Canada's provinces. For example, there's a Ruleset for "BC" for British
Columbia.

Example of a Ruleset for Canada and some of its provinces:

                  CA-->fr
                  |
-------------------------------------
|        |        |        |        |
v        v        v        v        v
AB-->fr  BC-->fr  MB-->fr  NB-->fr  NL-->fr

BUG=327046

Review URL: https://codereview.chromium.org/109323011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243754 0039d316-1c4b-4281-b951-d872f2087c98