Add portal_type title

[razvanMiu]

This adds a new field type to content response which contains the title of portal_type.

Example of why this is needed:
Let's say I have a content-type named Topic page with the id topic_page. Fetching a page of this content-type will respond with:

{
   '@type': 'topic_page',
   ...
}

There is no way to get the human readable title of the content-type so this pr will add a new field and the response will look like:

{
   '@type': 'topic_page',
   'type': 'Topic page',
   ...
}

[mister-roboto]

@razvanMiu thanks for creating this Pull Request and helping to improve Plone!

TL;DR: Finish pushing changes, pass all other checks, then paste a comment:

@jenkins-plone-org please run jobs

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass, but it takes 30-60 min. Other CI checks are usually much faster and the Plone Jenkins resources are limited, so when done pushing changes and all other checks pass either start all Jenkins PR jobs yourself, or simply add the comment above in this PR to start all the jobs automatically.

Happy hacking!

[erral]

Fixes partially #1322

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[avoinea]

@jenkins-plone-org please run jobs

[nileshgulia1]

@jenkins-plone-org please run jobs

[ksuess]

Assuming this is for Volto: A mapping from fti id to fti title can be received from state.types. No need to extend the serializers.

[avoinea]

@ksuess Can you detail a little. Is it available for anonymous users?

[ksuess]

@ksuess Can you detail a little. Is it available for anonymous users?

So issue description has to be read as "There is no way to get the human readable title of the content-type as long the user is Anonymous"

[nileshgulia1]

@jenkins-plone-org please run jobs

[nileshgulia1]

One thing I don't get is where to put the documentation about this extra field? Isn't it self-explanatory with being just added in http-examples?

[jensens]

One thing I don't get is where to put the documentation about this extra field? Isn't it self-explanatory with being just added in http-examples?

@stevepiercy may I head this one over to you?

[stevepiercy]

@jensens, I agree with @nileshgulia1. What do you think is needed in the way of documentation?

I found no place where the REST API authors have documented the keys in a response. Do they want to start?

[nileshgulia1]

@jenkins-plone-org please run jobs

[nileshgulia1]

@jenkins-plone-org please run jobs

[nileshgulia1]

@jenkins-plone-org please run jobs

[davisagli]

@jensens okay now from your point of view?

[avoinea]

@jenkins-plone-org please run jobs

[avoinea]

@jenkins-plone-org please run jobs