Multilanguage support + Add PT lang starting doc files

[lucianotonet]

Description

This purpose adds support for additional languages to the current documentation, as well adds a set of initial translations in Brazilian Portuguese. Additionally, I have updated the Gulp version 4 and made some improvements in those tasks and the build process. Now we are able to use Node v16.

Changes Made

• Added support for additional languages
• Changes the way to switch languages
• Added initial translations for Brazilian Portuguese
• Updated Gulp to version 4
• Made improvements in the Gulp tasks

Testing Done

I have tested it locally and verified that it works as expected. The cocos-docs build successfully and the new translations are displayed correctly.