[sitecore-jss-react] ErrorBoundary nested components fix

[yavorsk]

• This PR follows the Contribution Guide
• Changelog updated
• Upgrade guide entry added

Description / Motivation

This PR is a follow up to #1786 . It aims to fix an issue in the case where parent component is being used with withPlaceholder HOC and references its child components' props (this issue was caught in automated rendering tests for styleguide tabs component); since each child component is wrapped by ErrorBoundary, this adds additional level of nesting and changes the way parent should access its children's props; this is solved by exposing components props inside the error boundary.
This PR also:

• renames ErrorBoundary's customErrorComponent prop;
• updates failing Placeholder unit test to not select ErrorBoundary and check only html elements;

Testing Details

• Unit Test Added
• Manual Test/Other (Please elaborate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[illiakovalenko]

Looks good! 👍