search: Ensure CodeMeta dates are properly formatted

Some date values that can be found in codemeta.json files (dateCreated, dateModified, datePublished) might be in a format not parsable by elasticsearch which prevents successfull update of origin intrinsic metadata in elasticsearch indices.

For instance, the date 2021-7-23 cannot be parsed by elasticsearch as it expects 2021-07-23 instead.

So ensure to properly format CodeMeta dates to avoid such indexing errors.

This fixes the following sentry reported issue.

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Migrated from D6553 (view on Phabricator)