Feature. Replace instance object by generic type argument

[zubivan]

Instead of requiring the user to create an object as a placeholder for the return type we are leveraging Mendix generics, aka Entity Types (https://docs.mendix.com/refguide/java-actions#2-2-1-entity-type).

This should eliminate the need to create an extra object just to figure out the return type information.

Before:

After:

Overall changes:

Introduced a new Java Action - Execute_Query_New and marked Execute_Query as legacy, so our existing users won't get compilation errors when updating to the new version.

The main difference between the two is illustrated on this screenshot:

we are replacing the type parameter (which requires an object to be created) with entity type parameter that allows in place selection of a generic type.

[zubivan]

Please mark as WIP, I'll add a migration path for the old version.

[zubivan]

So, now instead of introducing a breaking change I introduced a new action and marked the old one as legacy. So at least for those who are using the module upgrade won't be painful.

[passalaqua]

This looks good, code-wise, but there are a few things we still need to do before releasing, namely:

• Update the documentation to describe the new functionality;
• (Maybe?) think of a better naming convention, instead of "ExecuteQuery_New". I would rather have a breaking change and rename the old one "ExecuteQuery_Old" and eventually remove it.
• Add test cases covering this new functionality.