feat(grails-gradle): move indy configuration from generated apps to Gradle plugin

[jamesfredley]

Summary

Move the Groovy invokedynamic (indy) configuration from generated build.gradle files to the Grails Gradle Plugin, centralizing the setting and providing user feedback.

Changes

• Add indy property to GrailsExtension (default: false)
• Configure GroovyCompile tasks in GrailsGradlePlugin to use the extension's indy setting
• Display lifecycle message explaining indy is disabled for performance and how to enable it
• Remove hardcoded indy=false from grails-forge template
• Remove hardcoded indy=false from grails-profiles base skeleton

User Experience

The message appears once per project during configuration:

> Configure project :
Grails: Groovy invokedynamic (indy) is disabled to improve performance (see issue #15293).
        To enable invokedynamic: grails { indy = true } in build.gradle

Users can enable indy in their build.gradle:

grails {
    indy = true
}

Testing

• ✅ grails-gradle-plugins compiles successfully
• ✅ grails-forge-core compiles successfully
• ✅ Message appears once during project configuration
• ✅ Application starts and runs correctly

Closes #15321

[jdaugherty]

#15321 was already closed by adding it to the gradle file.

Can you help me understand why you want to move this to the extension? The current implementation will break anyone who tries to override it - which is something significant enough that I think it should at least go into 7.1.x.

Are you wanting to change this default to true in Grails 8? That's the only reason I can think to move it to the extension.

[jdaugherty]

For anyone that generated an application with the 7.0.6+ codeline, it will now flip it back to false - making this a breaking change.

[bito-code-review]

The change introduces a configurable 'indy' option in GrailsExtension, defaulting to false, and removes the hardcoded 'indy = false' from build templates. For apps generated with 7.0.6+ that had this setting, behavior remains the same. However, existing apps without the explicit setting may see indy flipped from its previous default (likely true) to false, potentially causing a breaking change in performance or behavior.

[jamesfredley]

indy=false provides a massive performance improvement in Grails 7.x and I think we should consider making it the default without the extra config in build.gradle.

As we work on Grails 8 we may be able to achieve performance closer with some ideas from #15374 plus changes in Groovy.

[jdaugherty]

I'm good with this going into 7.1, but we need to update the upgrade guide to point out this difference. Can you add a blurb about this change?