Test Plugin Compatibility Check with Milestone and Snapshot Versions

[jamesfredley]

Issue description

https://github.com/grails/grails-core/blob/80792f89dc73f349f029c544786a7422f962859d/grails-core/src/main/groovy/grails/plugins/DefaultGrailsPluginManager.java#L398-L465

Test with a combination of plugins requiring a milestone or snapshot version and the current Grails version being a milestone or snapshot version.

The check produces a warning and not an error.

Plugin [myplugin:0.1.0-rc3] may not be compatible with this application as the application Grails version is less than the plugin requires. Plugin is compatible with Grails version 3.3.10 > * but app is 4.0.0