Inconsistent manifest env JSON value error handling between cf cli v6 and v7

Please fill out the issue checklist below and provide ALL the requested information.

• [ Y ] I reviewed open and closed github issues that may be related to my problem.
• [ Y ] I tried updating to the latest version of the CF CLI to see if it fixed my problem.
• [ Y ] I attempted to run the command with CF_TRACE=1 to help debug the issue.
• [ Y ] I am reporting a bug that others will be able to reproduce.

Describe the bug and the command you saw an issue with
When specifying a manifest env var with a JSON value, the value should be quoted so that it is treated as a string:

    env:
      JSON: '{ wasabi: { is: "good" }, i: { like: "wasabi" } }'

If the user mistakenly enters in the JSON without the quotes, a cf push using cf cli v6 will output a yaml error. However, a cf push using cf cli v7 will succeed and transform the JSON into a strange non-JSON format.

What happened
cf push v6 correctly displays an error to the user

cf push v7 succeeds but mangles the JSON

Expected behavior
I would expect the v7 push to display an error and abort the push

Exact Steps To Reproduce

Given the following manifest:

---
applications:
  - name: test-app
    buildpacks:
      - staticfile_buildpack
    env:
      JSON: { wasabi: { is: "good" }, i: { like: "wasabi" } }

v6 behavior

$ cf version
cf version 6.53.0+8e2b70a4a.2020-10-01

$ cf target
api endpoint:   https://api.run.nulldriver.com
api version:    2.150.0
user:           admin
org:            xtmp
space:          xtmp

$ cf push
Pushing from manifest to org xtmp / space xtmp as admin...
Using manifest file /Users/patrickcrocker/git/cf-cli-resource/spec/fixture/static-app/manifest.yml
yaml: unmarshal errors:
  line 5: cannot unmarshal !!map into string
FAILED

v7 behavior

$ cf7 version
cf7 version 7.2.0+be4a5ce2b.2020-12-10

$ cf7 target
API endpoint:   https://api.run.nulldriver.com
API version:    3.85.0
user:           admin
org:            xtmp
space:          xtmp

$ cf7 push
Pushing app test-app to org xtmp / space xtmp as admin...
Applying manifest file /Users/patrickcrocker/git/cf-cli-resource/spec/fixture/static-app/manifest.yml...
Manifest applied
Packaging files to upload...
Uploading files...

...removed for brevity...

     state     since                  cpu    memory    disk      details
#0   running   2020-12-12T17:16:09Z   0.0%   0 of 1G   0 of 1G

$ cf env test-app
Getting env variables for app test-app in org xtmp / space xtmp as admin...
OK

System-Provided:

...removed for brevity...

User-Provided:
JSON: {:i=>{:like=>"wasabi"}, :wasabi=>{:is=>"good"}}

No running env variables have been set

No staging env variables have been set

Notice the mangled format of the JSON env variable: {:i=>{:like=>"wasabi"}, :wasabi=>{:is=>"good"}}

Provide more context

• Mac OS X 10.15.7 iTerm

Notes regarding V6 and V7 CLI support:

• V6:
  • Minimum supported version of CF Deployment: v7.0.0 (CAPI Release: 1.74.0 (APIs 2.128.0 and 3.63.0))
  • Maximum supported version of CF Deployment: v13.4.0 (CAPI Release: 1.94.0 (APIs 2.149.0 and 3.84.0))
• V7:
  • Minimum supported version of CF Deployment: v13.5.0 (CAPI Release: 1.95.0 (APIs 2.150.0 and 3.85.0))

Start by reproducing the manifest env value case from the issue with cf push under CLI v7, then compare it with the v6 failure. Trace the manifest env handling used during push and verify how the unquoted mapping is converted. Done means v7 rejects the invalid value and aborts the push rather than storing the Ruby-style transformed representation.