Fix deprecations due to changes in ORM

[blafond]

Fixes #1714

Includes changes to uses of Loadable, EntityMetamodel, Type and getProperty()

[blafond]

Created ORM issue HHH-16999 and submitted a PR to help reduce redundancy and simplify reactive code

Will utilize these changes in ORM for this issue.

[blafond]

Created a draft PR for reactive changes

[DavideD]

Waiting for the next ORM 6.2 release

[DavideD]

Superseded by #1771