Support for accessing arbitrary profile config data (#3429)

## Motivation and Context
<!--- Why is this change required? What problem does it solve? -->
<!--- If it fixes an open issue, please link to the issue here -->
This is required to enable an upcoming service-specific env config
feature

## Description
<!--- Describe your changes in detail -->
This PR adds support for accessing profile config data defined in any
sort of section. It also supports sub-properties.

## Testing
<!--- Please describe in detail how you tested your changes -->
<!--- Include details of your testing environment, and the tests you ran
to -->
<!--- see how your change affects other areas of the code, etc. -->
I wrote tests

## Checklist
No changelog entry because this feature isn't publicly accessible yet.

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choice._

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Co-authored-by: John DiSanti <jdisanti@amazon.com>