Ensure that resource IDs passed into the use field exist and are in the
same resource group as the current resource.

Changes CheckResourcesAndGroupNames to be a standalone function that
returns error and ResourceToGroup map.

Also removed the -c flag from run_examples to remove the deprecation
warning.

Added a step in exand that applies any matching output in "use"
resources that matches the input of the current resource. In addition,
tests have been reorganized to decrease the size of the test_config.go
file.

Add tests for:
* getResourceByID
* useResource
* appendAsSlice
* getResourceByVarName

Various fixes to support tests also made

Adding a few function comments and cleaning up a test config

This commit adds the ability to use multiple resource output lists as a
single setting by merging the lists. This is done using the flatten
function in terraform and with a new feild in BlueprintConfig with
functions to be applied to settings in the main.tf file.

For simplicity, move applyFunctions into the YamlConfig so it can be
directly accessed during and after expand in the same way. This allows a
call to expand to produce a YAML that can be used again in create with
no differences in the final result.

The name was also changed to WrapSettingsWith to be more explanatory and
fit better under the Resource struct.

Moves expand() and validate() to the expand.go and validate.go file
respectively for clarity and to keep config.go as top-level as possible.

Makes a number of changes in the useResource and applyUseResource
function to decrease complexity and increase readabiltiy.

* Pass in resource Inputs and Used resource outputs directly to
UseResource rather than the ResourceInfo structs
* Improve Comment Clarity
* Improve error output details