weather-mv: Improve tool's efficiency in terms of time & memory.

[mahrsee1997]

Time Efficient:

Make use of gcloud alpha storage in open_local() method, sinks.py.

Findings -- using gsutil for downloading the data from gcs to the local file system is 5 times slower compared to gcloud alpha storage.

Memory Efficient:

Every time when we log xr_dataset.nbytes it will takes the complete dataset in-memory which is causing OOM killer invocation. TODO: Find a better way for logging the dataset size.

Real-time data ingestion into BQ:

beam.io.WriteToBigQuery() -- in case of batch pipeline data is not ingested into BQ in real-time. Because batch pipeline processes all elements before writing to BigQuery.

[mahrsee1997]

A temporary fix has been implemented on the mv-optimization branch (link). Further work is required to prepare the changes for merging.

[mahrsee1997]

Fixed:

• Time Efficiency: #315
• Memory Efficiency: #323