Split mojos into 3 plugins

[cstamas]

Having 65 mojo in one plugin is becoming unmaintainable. Instead:

• toolbox (existing) plugin could contain the gav--less mojos (those requiring project). They manipulate projects.
• gav-toolbox plugin could contain the gav-... mojos and CLI commands (w/ gav- prefix removed, as they are now separate plugin). This plugin is prefixed with gav- and is meant to manipulate resolvable GAVs
• hello is for Hello mojos

All 3 plugin would use same shared artifact.