OCR model migration The TEXT_DETECTION and DOCUMENT_TEXT_DETECTION models have been upgraded to newer versions

## Change **OCR model migration** The `TEXT_DETECTION` and `DOCUMENT_TEXT_DETECTION` models have been upgraded to newer versions. The API interface and client library will be the same as the previous version. The API follows the same Service Level Agreement. The legacy models can still be accessed until August 02 2022\. Specify "builtin/legacy" in the model field of a [Feature](https://cloud.google.com/vision/docs/reference/rest/v1/Feature) object to get the old model results. **After August 02, 2022 the legacy models will no longer be offered**.