Add support for general purpose cross referencing of named properties

We need to make sure that whatever syntax we have for cross referencing continues to work even as we look at adding more sources of configuration data.

examples: sysprops, late binding information from the registry to link to other components.

We may need to do something more typed, eg

{attr:property}

or even maybe

{@property}

,

{@/global/property}

to indicate attributes. And maybe even cross reference internal/resources

size:"

{@//resources/components/regions/yarn.component.instances}

"

Other references we could do with another syntax in the {}. Example

{env:Path}

,

{sysprop:java.home}

We'll need to allow for the { to be escaped somehow.