Update ogre2 ray query related functions to return Ogre::MovableObject instead of Ogre::Item

[iche033]

🎉 New feature

Summary

Addresses one of the todo items.

Ray query related functions in ogre2 now return Ogre::MovableObject instead of Ogre::Item (Ogre::Item is derived from Ogre::MovableObject). This is so that we can include heightmap ogre objects (which are Ogre::MovableObject typed objects) in the ray query results.

2 API changes are documented in the Migration guide. One of them (OnSelectionClick()) is a change to the return type so it can not be deprecated, i.e. API breaking change.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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