Fix wrong region code uses

Fix PartialFormatter for regions that are not the main country

The metadata number formats are only specified for the country
code's main country. Since PartialFormatter was using the metadata
of the region code, a region that is not the code's main country
would not have a format and PartialFormatter would leave the input
unchanged.

Fix by always using the main country for the region's country code.
This matches the behavior of libphonenumber.

Fixes for PhoneNumber type determination

Several fixes for determining the type of a phone number:

- Determine which metadata record to use based on the number's region,
  not the numeric country code. This fixes using the US metadata for all
  regions using country code 1, for example.
- Adjust the order we check the type regular expressions. The fixed and
  mobile patterns are the most generic so they should be checked last.
- Some fixes for regions with leading zeros
- Fix regex matchesEntirely - add parentheses to the expression

Also update testAllExampleNumbers to check that the expected type is
computed for all example numbers in the metadata.

Don't use possible number pattern to determine number type

The phone number type determination should never use the possible
number pattern, since that pattern is generic and not necessarily
specific to the type in question.

Update `isNumberMatchingDesc` to always use the national number pattern,
not the possible number pattern.

Also found and fixed a bug in RegularExpressions matchesEntirely while
making this change.

Implement regionCodeForNumber

Add the ability to get the region associated with a given number.
This is a fairly straightforward port of the algorithm implemented
in Google's libPhoneNumber:

- Get the metadata record(s) associated with the number's country code
- If there is only one record, return its region code
- If there are multiple records, use leadingDigits if present, otherwise
  fallback to checking all number formats

Make Constants public for easier subclassing

Put constants and patterns into a public struct
accessible outside project.

Make PartialFormatter's isValidNumber public.

Change build.sh to use generic `iphonesimulator`.

improvements to PartialFormatter region prediction