initializeEditor test helper supports Reassure performance tests

[dcalhoun]

What problem does this address?

The native mobile initializeEditor test helper is incompatible with the
recently added Reassure performance testing library. This incompatibility stems
from both Reassure and initializeEditor needing to control the render of the
component tree. In order to simplify writing performance tests for various block
types, we should refactor initializeEditor to support usage with Reassure.

#49221

What is your proposed solution?

An ideal design might resemble the following pseudo code:

await measurePerformance(<InitializeEditor initialHtml={paragraphMarkup} />, {
  scenario: typeWithinParagraph,
});