Adds "serverName" and "environmentName" to the alert template variable list.
Requires Java 9+.

Fixes NextGen request #6261.

Previous PR is #6262.

Slight tangent: I deleted KeyEncryptorTest to get over / ignore its java 9+ error that I don't care to investigate as I believe it's unrelated to this code change: error: package com.sun.crypto.provider is not visible.

Assuming we have documentation, it should be updated as two additional variables will display in the Alert Template variable list.

Test procedure:

1. Compile this patch with Java 9+ and start server
2. Login and get past initial account setup
3. Set Server Name and Environment Name under Settings tab
4. Import and deploy the two attached channels
5. Import the attached alert (remove its .txt extension after downloading)
6. Open the imported alert and validate two additional options are present on the right-hand side: "serverName" and "environmentName"
7. Validate the two additional options can be copied into the template text area
8. Send any message to channel "throws error"
9. Validate the resulting text in channel "Receiver" contains the Server Name and Environment Name as you defined in the Settings tab
10. Clear the Server Name and Environment Name under Settings tab, then re-run a message to ensure the alert template's values are replaced with empty strings

throws.error.xml.txt
Receiver.xml.txt
Foo.alert.xml.txt