Read env vars for server name and env name

[rogin]

Written to fix my own request here. NextGen merged it into their 4.6.0 release, so it's missing here.

Original test notes written here:

Used a freshly built server under /server/setup.

Start server with java -jar .\mirth-server-launcher.jar, and bring the server down after each test.

Test 1: No envvars set. Start server. Complete the admin change password modal. Validate values are blank in UI.
Test 2: set envvar MC_SERVER_NAME = 'Staging'. Start server. Validate its value in UI.
Test 3: set envvar MC_ENV_NAME = 'Sys-001'. Start server. Validate both values in UI.
Test 4: set envvar MC_SERVER_NAME = 'Prod', MC_ENV_NAME = 'Sys-002'. Start server. Validate both values in UI.
Test 5: Unset envvars MC_SERVER_NAME and MC_ENV_NAME. Start server. Validate both values in UI are same used in test 4 (as they've been stored in DB).

[jonbartels]

This PR eliminates the need for booter mcgooter

[tonygermano]

question: would the configuration controller be a more appropriate place for this functionality?

Or is there a reason it must be in Mirth.java?

[rogin]

question: would the configuration controller be a more appropriate place for this functionality?

Or is there a reason it must be in Mirth.java?

Yep, a single call to the controller is likely cleaner.