Feature: Set layout on render

[danielkhan]

This adds the option to specify a property layout when rendering ejs, dot, handlebar and eta templates.
Providing a layout globally or on render is mutually exclusive and an error will be thrown if both are set.

Docs look as if they could use a bit more structure and will be proposed in a separate PR.

Usage:

return reply.view('home', {}, { layout: './layouts/default' });

closes #276

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[climba03003]

Please remove the extra devDependencies, we use standard only.

[danielkhan]

Please remove the extra devDependencies, we use standard only.

This was copied from fastify and introduced and approved by @mcollina in #277.
Just making sure before rebasing this branch.

[mcollina]

lgtm with a question

[climba03003]

Please remove the extra devDependencies, we use standard only.

This was copied from fastify and introduced and approved by @mcollina in #277. Just making sure before rebasing this branch.

Does it means that the changes should be on #277 and it should not be in here?

[danielkhan]

Does it means that the changes should be on #277 and it should not be in here?

This feature branch is a fork of the branch containing #277. That's why I can easily rebase this one if these changes are unwanted.

[danielkhan]

Please remove the extra devDependencies, we use standard only.

This should now be all cleaned up

[climba03003]

Please remove the extra devDependencies, we use standard only.

This should now be all cleaned up

I think this PR can be closed because all your works is merged on #284
You can see that https://github.com/fastify/point-of-view/pull/278/files has no file changes