OpenRewrite best practices

Apply best practices to OpenRewrite recipes.

Recipes

• Add a blank line around fields with annotations
• Automatically select recipe examples from the unit test cases of a recipe
• Find OpenRewrite recipes
• Find missing @Option example values
• Minimal indentation for SourceSpecs text blocks
• Recipe classes should not have mutable static fields
• RewriteTest classes should not be public
• Set default estimated effort
• Use Tree.randomId() in LST constructors
• Use a standard name for ExecutionContext
• Use of @EqualsAndHashCode on Recipe