Adding e2e tests to blocks.

• Discussed how the @wordpress/scripts package contains the e2e testing tools
• Discussed how we also need @wordpress/env to run them.
• Created a basic e2e test suite to test if the block was inserted and that the content was correct
• Discussed using snapshots and the difference between toMatchSnapshot and toMatchInlineSnapshot
• Discussed how to pre-populate the test database with content using npm pre commands and the wp-env run command
• Created a test to ensure that the block saved test input by the user as the message attribute.