Portuguese langcode mismatch [#3333389]

Problem/Motivation

Portuguese langcode in drupal is "pt-pt". However in IntlDate's langcode=>locale mappings the langcode is "pt". Therefore in Portuguese language the dates come out in English.

Steps to reproduce

Enable Portuguese language.
Create a node in English with date output using intl_date.
Create a Portuguese translation
Open the translation

Expected output:
Portuguese date

Actual result:
English date

Proposed resolution

Change "pt" in the mapping to "pt-pt"

Issue fork intl_date-3333389

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3333389-portuguese-langcode-mismatch changes, plain diff MR !15
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