Unified Selection Support: Remove all deprecated references from iTwin.js 5.x in changed-elements-react

[diegopinate]

I updated the versions of core to 5.0.4 as part of this PR: #245. This work item should be addressed after this merges.

The Presentation.selection implementation has been marked deprecated. Gintaras created this issue that's related to the PropertyComparisonTable: #243, but we should ensure all unified selection uses the new package.

Besides that, please scan for any other deprecated function / classes used. We need to update all our deprecated code functions to use their new counterparts.

[hnn0003]

First round of changes derived from pineapple's version-compare, which mirrors much of the frontend code.
Next, worked on further changes to the frontend to support holding its own unified SelectionStorage object (which is needed now with the updates instead of the Presentation.selection keeping track of everything itself).
Then added changes to the SideBySideVisualizationManager.ts file in changed-elements-react package to require sending the unified SelectionStorage object as _selectionStorage, as any migration of Presentation.selection deprecated code will require using that SelectionStorage object that the frontend creates.

Branch with changes: heather/add-unified-selection
Some of the original code is still there commented out next to migrated versions of the same code, for easier comparison of old vs new

Current issues: elements are still not selected correctly. Elements are emphasized correctly, but when the 'isolate' button is hit, you can see that the model's selection set is empty (when it should have values).
Repro steps:

1. Run changed-elements on the branch heather/add-unified-selection and then open local model (http://localhost:2363/itwinjs/open-imodel/1036c64d-7fbe-47fd-b03c-4ed7ad7fc829/0db82dc1-e871-4209-b40a-6753c6a68c19?ChangeSetId=d2213a40fdebb793c732e5fd31c6786f243ceb2f)
2. Go to R3 Update
3. Click on '>' of ProcessPhysicalModel
4. Select the P-101 [3-1A2] changes
5. Hit the 'inspect properties' button for this (the P-101).
6. See that the selected element isn't highlighted blue, though it is emphasized with the black outline.
7. See that selecting the 'isolate' button doesn't correctly isolate things.
8. Repeat process in DEV-connect with the same model to see the differences: https://dev-connect-imodelweb.bentley.com/imodeljs/?projectId=1036c64d-7fbe-47fd-b03c-4ed7ad7fc829&iModelId=0db82dc1-e871-4209-b40a-6753c6a68c19&ChangeSetId=d2213a40fdebb793c732e5fd31c6786f243ceb2f

Useful Links:

• heather/add-unified-selection branch
• unified-selection general readme
• unified-selection migration guide
• More links on migration tips can be found in the iTwinpresentation unified-selection package's learning folder, or there are links within the migration guide above that you can follow.
• Pineapple's changed-elements-react code, some of it mirrors the frontend code
• Change history with itwinjs-core migration of some unified-selection changes
• Discussion with Jason (pineapple) on old scope naming vs new scope naming

Notes:

• Not sure how much further updating of deprecated functionality in the front-end should be done, as theoretically, one goal of that is to mirror pineapple itself, which doesn't seem to have fully migrated all of its deprecated code there. SImilar code generally has the same file names and is found in either the changed-element-react folder or the PropertyComparisonFrontstage subfolder