[MNG-8346] Reorganize subprojects

[gnodet]

JIRA issue: MNG-8346

• Script for refactoring
• Refactor: Reorganize Maven modules into impl and compat directories (this is just the execution of the previous script)

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The Maven 4 branch has a bunch of new projects that have been added over the last years, with some incoherent naming. This PR is about moving the files around to make things easier to grasp.
Reorganize subprojects with:

.
├── build
├── api
│   ├── maven-api-cli
│   ├── maven-api-core
│   ├── maven-api-di
│   ├── maven-api-meta
│   ├── maven-api-metadata
│   ├── maven-api-model
│   ├── maven-api-plugin
│   ├── maven-api-settings
│   ├── maven-api-spi
│   ├── maven-api-toolchain
│   ├── maven-api-xml
├── impl
│   ├── maven-cli
│   ├── maven-core
│   ├── maven-di
│   ├── maven-impl
│   ├── maven-jline
│   ├── maven-logging
│   └── maven-xml
├── compat
│   ├── maven-artifact
│   ├── maven-builder-support
│   ├── maven-compat
│   ├── maven-embedder
│   ├── maven-model
│   ├── maven-model-builder
│   ├── maven-plugin-api
│   ├── maven-repository-metadata
│   ├── maven-resolver-provider
│   ├── maven-settings
│   ├── maven-settings-builder
│   ├── maven-toolchain-builder
│   └── maven-toolchain-model
├── maven-docgen
└── apache-maven

This needs to be considered in light of #1829.
Also, this will give more room for integrating ITs back.