Expand EntityCrawlerTrait to allow any render array

Problem/Motivation

We have getRenderedEntityCrawler and getBlockPluginCrawler that have some common parts, being:

• Get a render array
• Render it
• Get a symfony crawler
• Generate HTML output

These are great, but sometimes you just want to do the same for and miscellaneous render array.

Steps to reproduce

Proposed resolution

• Introduce ::getRenderArrayCrawler
• Refactor ::getRenderedEntityCrawler and ::getBlockPluginCrawler to use ::getRenderArrayCrawler
• Consider renaming the trait RenderCrawlerTrait or just CrawlerTrait and deprecate the existing trait

Remaining tasks

User interface changes

API changes

Data model changes