fix: allow CONTENT_TYPE env to work for all oclif cmds

[mshanemc]

read CONTENT_TYPE=json from the env

forcedotcom/cli#2331
@W-13848014@

before/after

QA:
compile this
yarn link into oclif/plugin-version
sf plugins link . (inside oclif/plugin-version). This is needed to get the SF into the scopedEnvVars. Otherwise (bin/dev), you've got to do it with the plugin, but note that the @ | /| - are transformed by oclif config/scopedEnvVars
SF_CONTENT_TYPE=json sf version

[mdonnalley]

there's an .env() on fancy-test that lets you set env vars if you prefer

[mshanemc]

that didn't work when I tried it

[WillieRuemmele]

QA Notes

---

Following the QA instructions above, confirmed working
✅

 ➜  SF_CONTENT_TYPE=json sf version
{
  "cliVersion": "@salesforce/cli/2.1.7",
  "architecture": "darwin-arm64",
  "nodeVersion": "node-v18.16.0"
}

✅ : jqable results

➜  plugin-version git:(main) 🔗1
 ➜  SF_CONTENT_TYPE=json sf version | jq .cliVersion
"@salesforce/cli/2.1.7"

✅ : confirmed NOT working in plugin-commands before linking

 ➜  SF_CONTENT_TYPE=json sf commands                
 Command                               Summary                                                                                                                             
 ───────────────────────────────────── ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 
 alias list                            List all aliases currently set on your local computer.  

✅ : working after linking

 ➜  SF_CONTENT_TYPE=json sf commands
[
  {
    "id": "alias:list",

✅ : jqable

 ➜  SF_CONTENT_TYPE=json sf commands|jq '.[0].id'
"alias:list"

✅ : doesn't override flag

 ➜  SF_CONTENT_TYPE=notjson sf commands --json|jq '.[0].id'
"alias:list"