Add consumer ID "squish_info"

The "old" Squish floating license model knows three kinds of license purposes or, in QLS speak, consumer IDs:

• squish_tester
• squish_executor
• squish_installer

Currently, only the first two consumer IDs are supported by QLS. The third one is still missing.

In QLS, squish_installer should be called squish_info to reflect the use case better. The Squish installer and squishrunner use it to query license information, for example in squishrunner --info wrappers. The intention is to make installation and informational queries always work, even if all tester and executor licenses are reserved.

A license request with squish_info must be refused if no valid Squish license exists.