fix(scratch): respect apiVersion config value

[cristiand391]

What does this PR do?

Fix scratch org create code that deploys settings not respecting the apiVersion config value by correctly instantiating the ConfigAggregator class.

Before:
even having apiVersion set locally/globally, the code always gets undefined.

After:
code respects config value.

QA:
see gh issue linked below for debug env var val

this code is used by sfdx force:org:create and sf env create scratch/sf env resume scratch.
make sure the following config values/env vars are respected:

config values:
org-api-version
apiVersion

env vars:
SFDX_API_VERSION
SF_ORG_API_VERSION

What issues does this PR fix or reference?

forcedotcom/cli#1719
@W-11798656@

[mshanemc]

I checked the rest of the repo for other uses of .getPropertyValue('apiVersion') and this was the only one.

[peternhale]

Testing notes:

 sfdx config:set apiVersion=47.0 --global
=== Set Config
 
 Name       Value Success 
 ────────── ───── ─────── 
 apiVersion 47.0  true    

Before

DEBUG=sf:deploySettingsViaFolder sfdx force:org:create -s -f config/project-scratch-def.json -a foo -v na40 -w 30
WARNING: apiVersion configuration overridden at "47.0"
  sf:deploySettingsViaFolder DEBUG deploying to apiVersion: 55.0 +0ms
  sf:deploySettingsViaFolder DEBUG deploying settings id 0Af8H000007ahD6SAI +501ms
  sf:deploySettingsViaFolder DEBUG Deploy id: 0Af8H000007ahD6SAI status: InProgress +1s
  sf:deploySettingsViaFolder DEBUG Deploy id: 0Af8H000007ahD6SAI status: Succeeded +2s
Successfully created scratch org: 00D......., username: [email protected].

After

DEBUG=sf:deploySettingsViaFolder sfdx force:org:create -s -f config/project-scratch-def.json -a foo -v na40 -w 30
WARNING: apiVersion configuration overridden at "47.0"
(node:73903) Warning: Setting the NODE_TLS_REJECT_UNAUTHORIZED environment variable to '0' makes TLS connections and HTTPS requests insecure by disabling certificate verification.
(Use `node --trace-warnings ...` to show where the warning was created)
  sf:deploySettingsViaFolder DEBUG deploying to apiVersion: 47.0 +0ms
  sf:deploySettingsViaFolder DEBUG deploying settings id 0Af8F000009m8V8SAI +520ms
  sf:deploySettingsViaFolder DEBUG Deploy id: 0Af8F000009m8V8SAI status: InProgress +1s
  sf:deploySettingsViaFolder DEBUG Deploy id: 0Af8F000009m8V8SAI status: Succeeded +2s
Successfully created scratch org: 00D8..................., username: [email protected].