Fix and Improve sql logging coloration in ActiveRecord::LogSubscriber.

[pboling]

• Fixes coloring for SQL statements generated with Ruby heredoc, which often have spaces preceding the initial SQL verb, like:

   sql = <<-EOS
      SELECT * FROM THINGS
        WHERE ID IN (
          SELECT ID FROM THINGS
        )
   EOS

^ Would be colored as MAGENTA in the existing code.

• Improves coloring for statements like:

    # Become WHITE
    SELECT * FROM (
        SELECT * FROM mytable FOR UPDATE
    ) ss WHERE col1 = 5;
    LOCK TABLE table_name IN ACCESS EXCLUSIVE MODE;

    # Becomes RED
    ROLLBACK

• Reinstates the coloration of the payload[:name] via new method:
  colorize_payload_name
  Instead of simple alternating colors, adds meaning:
  • MAGENTA for "SQL" or blank? payload names
  • CYAN for Model Load/Exists
• Make some ActiveRecord::LogSubscriber instance methods private for clarity:
  • colorize_payload_name
  • sql_color
  • logger
• Introduces specs for sql coloration.
• Introduces specs for payload name coloration.

GH #20885

[egilburg]

don't need then keywords if using multi-line case statement.

[pboling]

Thanks. I am still used to writing code that is backwards compatible with Ruby vOLD. :P

Fixed.