Create LICENSE

[sammitachak]

Added a collated LICENSE file at the root level directory. The licenses are as per the LICENSES folder (https://github.com/liferay/liferay-portal/tree/master/LICENSES). This is majorly for the Github API for license fetch to work for this repository.

(Please note that the Copyright year and owner fields have been intentionally left empty since Google LLC doesn't own this repository)

[CLAassistant]

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