Fix a bug in pulumi config env ls json output

[komalali]

Description

The --json flag for pulumi config env ls was not being correctly passed through, this fixes the issue. Also changed the default output of no envs from null to [] so automation api doesn't need to handle the null case in all languages.

Checklist

• I have run make tidy to update any new dependencies
• I have run make lint to verify my code passes the lint check
  • I have formatted my code using gofumpt

• I have added tests that prove my fix is effective or that my feature works

• I have run make changelog and committed the changelog/pending/<file> documenting my change

• Yes, there are changes in this PR that warrants bumping the Pulumi Cloud API version

[pulumi-bot]

Changelog

[uncommitted] (2023-12-20)

Bug Fixes

• [cli/config] Fix a bug in pulumi config env ls --json where the json flag was not being correctly passed through.
  #14961