fix Issue #8953- add Extension Manager support for localized extension package metadata.
update localization example for reference
update localization readme for reference
as requested per code review
changes per code review
Merge remote-tracking branch 'origin/master' into bchin/localize-package-metadata
per code review, overlay first by shortlang, then by lang.
Merge remote-tracking branch 'origin' into bchin/localize-package-metadata
whitelisting properties to overlay; remove keyword concatenation with root language
add top-level key to package.json to avoid collisions
changes per code review
adding unit tests
changes as requested per code review
Further consolidate duplicated code in a unit test
Merge pull request #8987 from adobe/bchin/localize-package-metadata

fix Issue #8953- "Localizing package metadata in Extension Manager"