Fix arg order for Storage Emulator start command

[tohhsinpei]

Description

Issue

The Storage Emulator crashes on start for me on OpenJDK 11.0.12. The only error logs are

$ firebase emulators:start --only storage
i  emulators: Starting emulators: storage

Error: There was an issue starting the rules emulator, please run 'firebase setup:emulators:storage` again

Error: Storage Emulator Rules runtime exited unexpectedly.

Cause

The args passed in the start command are in the wrong order: java -jar -Duser.language=en <jarfile> serve instead of java -Duser.language=en -jar <jarfile> serve as recommended. This causes -Duser.language=en to be mistakenly interpreted as the JAR file:

Error: Unable to access jarfile -Duser.language=en

This PR also adds the above message to the error logs.

Scenarios Tested

Tested the above commands on the command line to confirm that the program launches successfully with the new order:

{"result":{},"id":-1,"status":"ok"}

Also verified that the Storage Emulator is launched successfully with the fix.

[yuchenshi]

Please also add a CHANGELOG entry