Fix AsYouTypeFormatter dropping parens from rule-based formats (BR, RU, CO)

[PetroczyP]

Summary

Fixes Issue Tracker #437456062
where AsYouTypeFormatter drops the parenthesis literals from countries whose
national format derives them from nationalPrefixFormattingRule rather than
from the inline <format> template — most visibly for BR mobile, RU mobile,
and CO. Static format() already produces the parens correctly using the
same metadata; the bug is isolated to AYTF's template-build path, which only
ever read getFormat() and ignored getNationalPrefixFormattingRule()'s
wrap.

Fix

A small private helper — applyNationalPrefixFormattingRule (Java) /
ApplyNationalPrefixFormattingRule (C++, PascalCase per Google C++ style) /
applyNationalPrefixFormattingRule_ (JS, with the Closure private-name
underscore) — is invoked at two sites in each language,
createFormattingTemplate and attemptToFormatAccruedDigits, to splice the
rule's punctuation into the format string before the existing template
substitution runs. Three branches:

1. Empty rule or international-mode → return the bare format unchanged
   (preserves current behavior for US, AR, DE, etc. and for the
   format(num, INTERNATIONAL) rendering path).
2. Rule begins with the national prefix (e.g. "$NP $FG" after metadata
   substitution → "0 $1" for GB, "8 $1" for RU): strip the leading prefix
   plus any adjacent separator, then splice the remainder. The trunk prefix
   continues to render separately via prefixBeforeNationalNumber, so this
   avoids doubling it.
3. Rule contains the prefix in a position not stripped (e.g. GB
   "($NP$FG)" which wraps the prefix inside literal punctuation): return
   the bare format. Splicing such a rule would duplicate the trunk prefix
   that AYTF renders separately.

A complementary defensive fallback at the country-code-extraction function
(attemptToExtractCountryCallingCode in Java, AttemptToExtractCountryCode
in C++, attemptToExtractCountryCallingCode_ in JS) preserves the
"currentMetadata is never null" invariant the helper relies on: when the
country code maps to a non-geographical region (e.g. +800 toll-free) and
getMetadataForNonGeographicalRegion returns null because the metadata
isn't loaded, fall back to the existing EMPTY_METADATA sentinel. Same
pattern as the constructor and the regular-region path.

Test plan

• BR fixed-line: (11) 3234-5678 rendered char-by-char against region BR.
  Single test method per language asserts every digit boundary, covering
  both the final-step assertion and the intermediate steps where parens
  first materialise. (BR test metadata only carries a fixed-line
  numberFormat; the ($FG) rule shape is identical to production BR
  mobile, so a fix verified on BR fixed-line covers the reported BR
  mobile case.)
• RU mobile: 8 (912) 345-67-89 rendered char-by-char against region RU,
  including the closing ) that materialises only after a later
  subscriber digit advances lastMatchPosition past it (transition
  8 (912 → 8 (912) 3 at digit 5).
• CO breadth: (601) 1234567 rendered char-by-char against region CO,
  same ($FG) rule shape on a different pattern length to prove the fix
  is structural rather than BR-specific.
• International-format regression: +55 11 3234-5678 rendered against
  region ZZ to confirm the isInternationalMode short-circuit returns
  the bare format (matching format(num, INTERNATIONAL)).
• Pre-existing US (no rule), AR (rule $NP$FG), GB (rule ($NP$FG))
  AYTF tests all continue to pass — the no-change paths are byte-identical.
• Full Java suite: mvn -pl libphonenumber -am test -B → 287 tests pass,
  0 failures.
• Full C++ suite: ./libphonenumber_test → 331 tests pass across 16
  suites, 0 failures.
• Full JS suite: python -m scripts.run_js_tests → all 3 test pages
  (phonenumberutil, asyoutypeformatter, shortnumberinfo) green via
  Closure jsunit + Playwright.

CONTRIBUTING.md compliance

• CLA signed (Google Individual CLA on petroczyp@gmail.com,
  2026-05-02).
• Bug fix, not a metadata edit. resources/PhoneNumberMetadata.xml
  and all auto-generated metadata derivatives are unchanged. The only
  metadata-XML edit is to PhoneNumberMetadataForTesting.xml (test
  fixtures) plus its regenerated derivatives (test_metadata.cc,
  PhoneNumberMetadataProtoForTesting_{BR,CO,RU}, metadatafortesting.js).
• Three-language port: Java + C++ + JS in the same PR per the
  cross-language porting expectation. Every change in
  AsYouTypeFormatter.java has a parallel in asyoutypeformatter.cc
  and asyoutypeformatter.js.
• Minimal-diff: ~30 LOC source + ~80 LOC test per language; no public
  API surface changed; applyNationalPrefixFormattingRule[_] is
  private in all three.
• No documentation outside the source files; no README updates; no
  docstring sweeps.

Files

Language	Source	Test	Test fixtures
Java	java/libphonenumber/src/com/google/i18n/phonenumbers/AsYouTypeFormatter.java	java/libphonenumber/test/com/google/i18n/phonenumbers/AsYouTypeFormatterTest.java	data/PhoneNumberMetadataProtoForTesting_BR, _CO, _RU
C++	cpp/src/phonenumbers/asyoutypeformatter.h, .cc	cpp/test/phonenumbers/asyoutypeformatter_test.cc	cpp/src/phonenumbers/test_metadata.cc
JS	javascript/i18n/phonenumbers/asyoutypeformatter.js	javascript/i18n/phonenumbers/asyoutypeformatter_test.js	javascript/i18n/phonenumbers/metadatafortesting.js

Test fixtures and test_metadata.cc are regenerated outputs of
BuildMetadataProtoFromXml / BuildMetadataCppFromXml /
BuildMetadataJsonFromXml against resources/PhoneNumberMetadataForTesting.xml.