Review naming rules in new `$JETTY_BASE/environments/` directory.

**Jetty version(s)**
12.1.x

**Enhancement Description**
The newly introduced `$JETTY_BASE/environments` directory is currently exclusive for use by the jetty-deploy features.

And the naming follows the convention...

* `.xml` (eg: `ee10.xml`)
* `-.xml` (eg: `ee10-audit.xml`)

Where the XML files are applied to a `ContextHandler`, in alphabetical order.

But how about introducing the ability to configure an environment, not a ContextHandler.
This would occur once, and be run before any webapps are deployed.
This would need a new naming scheme, or a reserved word.

Eg:

* `$JETTY_BASE/environments/start-ee8.xml`
* `$JETTY_BASE/environments/setup-ee8.xml`
* `$JETTY_BASE/environments/ee8-setup.xml`

One or more XMLs could be used to initialize the environments (eg: setup JNDI references, initialize components, etc), where all deployed webapps benefit.

Start by tracing how the existing $JETTY_BASE/environments directory is handled by the jetty-deploy features and where deployment creates or configures ContextHandlers. Compare the proposed naming schemes with the deployment lifecycle; done requires an agreed approach for one-time environment initialization before webapps are deployed, with its behavior and naming documented.

Written by the indexing model from the issue text.