Prepare to make all Elyra-owned properties object-valued

[kiersten-stokes]

Supports #2942. This PR to be merged before merge of the shared memory PR.

What changes were proposed in this pull request?

This PR introduces some implementation details that simplify the addition of new properties by making all properties object-valued. The bulk of the change is the renaming of the ui_details_map to attribute_details, and also includes a major change to the data structure. Whereas before this structure was a dictionary, it is now a list of PropertyAttribute objects, each of which contains the information needed to render and process a single property attribute (e.g. "env_var" and "value" are the PropertyAttributes for the EnvironmentVariable class). Additionally, the creation of the properties schema now assumes that all properties are either objects or arrays (with the exception of DisableNodeCaching, explained below). All the above allows us to generalize, and removes the need for a create_instance method on each class.

Note that the DisableNodeCaching property is still single-valued for now. The reason being that fully converting this property to an object would require a pipeline migration, and we would like to avoid a migration so soon after the 3.12 migration, if possible.

No changes to the frontend are included or necessary, unless we decide that we want to migrate DisableNodeCaching.

Finally, a distinction is made between Elyra-owned properties (those with a corresponding ElyraProperty class) and properties that should be propagated. There is currently only one case where the set of propagated properties != the set of Elyra-owned properties, which is the propagation of runtime_image for generic components. This is handled in a new property on the Node object called propagated_properties, which is accessed in the node propagation loop.

How was this pull request tested?

Manually tested several scenarios. Changes are self-contained and only one minor test update was required.

Developer's Certificate of Origin 1.1

   By making a contribution to this project, I certify that:

   (a) The contribution was created in whole or in part by me and I
       have the right to submit it under the Apache License 2.0; or

   (b) The contribution is based upon previous work that, to the best
       of my knowledge, is covered under an appropriate open source
       license and I have the right under that license to submit that
       work with modifications, whether created in whole or in part
       by me, under the same open source license (unless I am
       permitted to submit under a different license), as indicated
       in the file; or

   (c) The contribution was provided directly to me by some other
       person who certified (a), (b) or (c) and I have not modified
       it.

   (d) I understand and agree that this project and the contribution
       are public and that a record of the contribution (including all
       personal information I submit with it, including my sign-off) is
       maintained indefinitely and may be redistributed consistent with
       this project or the open source license(s) involved.

[elyra-bot]

Thanks for making a pull request to Elyra!

To try out this branch on binder, follow this link:

[kevin-bates]

This refactoring is great! Just had a few minor comments and nits.

[kevin-bates]

Good stuff - thank you!

[ptitzler]

LGTM!