Enhancement to API for View: Return ViewRowData

[lbwexler]

• Remove unnecessary and undocumented _meta pointer in BaseRow
• Provide new documented class for the object that is returned, with dynamic support for looking up leafRows.

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• Caught up with develop branch as of last change.
• Added CHANGELOG entry, or determined not required.
• Reviewed for breaking changes, added breaking-change label + CHANGELOG if so.
• Updated doc comments / prop-types, or determined not required.
• Reviewed and tested on Mobile, or determined not required.
• Created Toolbox branch / PR, or determined not required.

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[amcclain]

Hi - started to read through, ended up editing/enhancing (I hope) a bunch of doc comments as I tried to understand this system again. Don't know that I quite understand it yet, but certainly didn't see any issues and am eager to adapt the small number of _meta usages I know of to the new API - seems like it will be a big improvement!

[amcclain]

This is a map of all rows (at all levels?) by their BaseRow.id?

[amcclain]

This has been great to re-engage with our data package here.

The API updates seem like clear improvements - make me eager to add some more long-desired features, but I can hold back on my wishlist for future merges.

I would be happy for this to be merged at any point, but to be clear I haven't attempted to replicate or asses any findings around memory retention or the actual changes that prompted this work. And apols for blowing up the size of the changeset here with all of my comment updates - it was a good prompt to take another pass over all of that, didn't mean to hijack this PR so much. :)

@haynesjm42 leave it to you and Lee if there's anything else you want to suggest or test on this before merging and continuing the investigations.