Extract annotation processor classes and writers out of the runtime dependencies. Consider renaming `inject-java`.

[dstepanov]

Issue description

Right now inject module contains a lot of classes that are only used at the compilation time and can be removed from the runtime:

• io/micronaut/inject/ast - AST that is used during the annotation proccessing
• io/micronaut/inject/writer - Writers used to generate classes
• io/micronaut/inject/visitor - Annotation processor visitors
• io/micronaut/inject/beans - Bean introspection writers, mappers
• io/micronaut/inject/configuration - Configuration metadata writers
• io/micronaut/inject/processing - Utils
• io/micronaut/inject/util - Utils

The module name inject is a bit misleading because there is a lot more stuff happening. We should consider renaming it to core-processor just like data-processor in Micronaut Data. Different language-specific implementations can be core-processor-java, core-processor-groovy.

WDYT @micronaut-projects/core-developers ?

[melix]

In case inject-java is renamed, the Gradle (and probably Maven) plugins will have to be adapted (as well as the Micronaut Build tools) as there are several occurrences there.

[graemerocher]

don't think it is worth renaming it would create too much disruption. However moving the compile time only types out of micronaut-inject and eliminating the repacking of ASM into the runtime jars is a must.

[sdelamo]

+1 from me @dstepanov

[jameskleeh]

I don’t see much benefit in renaming the inject- modules.

[graemerocher]

I don’t see much benefit in renaming the inject- modules.

agreed, will just create disruption, new compilation time only modules makes sense though

[graemerocher]

Fixed by https://github.com/micronaut-projects/micronaut-core/pull/8224