Add opts.message option to code frames

[jamiebuilds]

This adds the ability to add inline messages to code frames.

With line and column:

  1 | class Foo {
> 2 |   constructor()
    |                ^ Missing {
  3 | };

With line:

  Missing {
  1 | class Foo {
> 2 |   constructor()
  3 | };

With start and end line and column:

  1 | class Foo {
> 2 |   constructor() {
    |                 ^
> 3 |     console.log(arguments);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 4 |   }
    | ^^^ something about the constructor body
  5 | };

With start and end line:

  something about the constructor body
  1 | class Foo {
> 2 |   constructor() {
> 3 |     console.log(arguments);
> 4 |   }
  5 | };

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/6674/

[xtuc]

Looks nice. Could you please update the documentation with the new option?

[existentialism]

👍

[jamiebuilds]

Added some docs