add WES API endpoint information to output from `agc context describe`

[wleepang]

Description

Add the WES API endpoint url for a context as part of the output from agc context describe <context-name>

Use Case

Users that write applications that speak GA4GH WES and leverage AGC to manage contexts need a way to retrieve the endpoint to talk to after the context has already been deployed.

Proposed Solution

Add a WESENDPOINT to the output from agc context describe <context-name>

$ agc context describe spotCtx
2021-12-10T23:42:58Z �  New version of agc available. Current version is '1.1.1'. The latest version is '1.1.2'
2021-12-10T23:42:58Z �  Describing context 'spotCtx'
CONTEXT 256     spotCtx true    STARTED 
OUTPUTLOCATION  s3://agc-733263974272-us-east-2/project/Demo/userid/pwymingJKP3z/context/spotCtx
WESENDPOINT  https://d1jhugndd0.execute-api.us-east-2.amazonaws.com/prod/ga4gh/wes/v1

Other information