Add support for storing assets in S3

[busma13]

This PR makes the following changes:

• Add S3Store class to teraslice which will store a zipped asset external to ES. Asset metadata is still stored in ES.
• Adds the following fields to terafoundation:
  • asset_storage_connection_type
  • asset_storage_connection
  • asset_storage_bucket
• Add check for asset_storage_connection_type in AssetsStorage class. If value is S3 create an s3Backend to store assets externally.
• Update AssetsService class:
  • Add an external_storage column to the get /txt/assets and get /assets endpoints to show if the asset is available or missing.
• Add new tests to simple-spec.ts in e2e that ensure assets are stored in S3.
• Add s3_store-spec.ts, assets_storage-spec.ts, and assets-spec.ts to teraslice test suite.
• Add new job to github test workflow that runs e2e tests with external asset storage.

Ref: #3561

[godber]

Is assetSearch called once on job startup or once per worker?

https://github.com/terascope/teraslice/blob/dad488eedd7230805abcb11289463e196834341f/packages/teraslice/src/lib/cluster/services/assets.ts#L219

[sotojn]

Is assetSearch called once on job startup or once per worker?

https://github.com/terascope/teraslice/blob/dad488eedd7230805abcb11289463e196834341f/packages/teraslice/src/lib/cluster/services/assets.ts#L219

assetsearch is called whenever you hit the v1/assets or the txt/assets endpoints. The only other code I see using those endpoints are inisde the teraslice-client-js

Also the only thing I see that utilizes the teraslice-client-js package is teraslice-cli.