fix(data-table): do not overwrite row.cells property

[metonym]

Currently, DataTable will add a cells property to each row which contains computed metadata for each header (e.g., key, display value, resolved value if using nested headers).

This is undesirable as it overrides the "cells" property in a row.

Although technically a breaking change, I'm considering this a fix as no row properties should be overridden in the first place.

Additional changes:

• chore: touch up prop descriptions (use periods where needed)
• refactor: remove unneeded third argument in resolvePath()
• perf: when resolving path, early return object[path] if value exists

[metonym]

Fixed in v0.65.0