Feature Request: Contact(sending feedback to contacts) API endpoint

[ChengShi-1]

Overview of the Feature Request
In SPA, users are allowed to send feedback to contacts of a collection, dataset or file.
Input would include subject, message, from (email autocomplete if login, or filled out by guest users).

In Native API, it has a similar API endpoint sending feedback to contact, but it is under admin path, and it returns contacts' email that could be sensitive. Send Feedback To Contact(s)

What kind of user is the feature intended for?
API User and all SPA users

What inspired the request?
SPA Q4.9
IQSS/dataverse-client-javascript#232

[stevenwinship]

@ChengShi-1 @pdurbin @qqmyers
Please comment on the following warning about email spam from the current FeedbackApi:

/**
* This method mimics the contact form and sends an email to the contacts of the
* specified Collection/Dataset/DataFile, optionally ccing the support email
* address, or to the support email address when there is no target object.
*
* !!!!! This should not be moved outside the /admin path unless/until some form
* of captcha or other spam-prevention mechanism is added. As is, it allows an
* unauthenticated user (with access to the /admin api path) to send email from
* anyone to any contacts in Dataverse. (It also does not do much to validate
* user input (e.g. to strip potentially malicious html, etc.)!!!!
**/

[pdurbin]

The comment was added by @qqmyers in #9186 and looks accurate to me.

I added the submitFeedback method itself in #4571 along with API tests that call into it. The method was only meant for testing, for making assertions about the behavior of the app.