Add http://{endpoint_address}:{s3_port}/_/version api to the endpoint

[romayalon]

Explain the changes

1. Create an API for receiving the package version of NooBaa via the endpoint.

Issues: Fixed #xxx / Gap #xxx

1. Gap - add a CLI call for that?
2. move other internal apis to be under /_/

Testing Instructions:

Happy path manual Test -

1. Tab 1 - sudo node noobaa-core/src/cmd/nsfs.js --debug 5
2. Tab 2 - call the new /_/version api -

> curl http://localhost:6001/_/version
5.19.0%

Bad path manual test -

1. Tab 1 - sudo node noobaa-core/src/cmd/nsfs.js --debug 5
2. Tab 2 - call the new /_/version1 api -

> curl http://localhost:6001/_/version1
{"error":"Internal Server Error","message":"Unknown API call version1"}%

• Doc added/updated
• Tests added