CLI-1250: Update CXAPI spec to add environments:mod-proxy-status

[danepowell]

Motivation

Provides access to new commands like environments:mod-proxy-status

Proposed changes

I've hacked the cx api spec to treat date times as string literals. This really needs to be fixed upstream though, it's not sustainable to override it.

Also, while the API now supports hal+json and this makes up the majority of example responses in the spec, we will stick with application/json for actual requests for now and just translate any hal+json responses from the spec to json. At some point we should probably start accepting hal+json (ideally once the ACSF API supports it as well).

Alternatives considered

Testing steps

1. Follow the contribution guide to set up your development environment or download a pre-built acli.phar for this PR.
2. Clear the kernel cache to pick up new and changed commands: ./bin/acli ckc
3. (add specific steps for this pr)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.22%. Comparing base (2abfc91) to head (9e09c32).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1699 +/- ## ============================================ - Coverage 91.23% 91.22% -0.02% Complexity 1794 1794 ============================================ Files 122 122 Lines 6448 6448 ============================================ - Hits 5883 5882 -1 - Misses 565 566 +1 ```

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