Add raw value validation to multiple text strings property editor

[kjac]

Prerequisites

• I have added steps to test this contribution in the description below

Description

#18581 added server-side validation for the min/max configuration of the multiple text strings editor 💪

Unfortunately, the IValueValidator receives different property values for different actions; specifically the "save" and "publish" actions yield different values:

• "save" yields the IDataEditor.ToEditor() format.
• "publish" yields the raw property data format (from the DB).

Eventually we need to streamline this, but for the time being... we need to make sure our validators handle both formats. Hence, this PR "fixes" the validator for the multiple text strings editor.

Testing this PR

Verify that the multiple text strings editor work with min/max validation for both save and publish 😄

[AndyButland]

Code looks good, tests pass, and I can verify we get correct responses from the /umbraco/management/api/v1.1/document/{id}/validate end point.

But I'm a bit confused as to what I should test or expect from the UI. What I see, when creating a new document with a multiple text strings property configured with a minimum of 1 and a maximum of 2, is:

• Click save with no strings added, saves without any validation error.
• Click save and publish, get an error message of "This field need more items" but this is different to the message returned from the validate endpoint, which is "The 0 items provided are less than the allowed minimum of 1"
• Add two strings, save and published, all fine as expected.
• Add an extra string, get an immediate client-side validation error of "This field exceeds the allowed amount of items"
• Hit save and publish, briefly see the validation message that comes back from the validate endpoint - "The 3 items provided are greater than the allowed maximum of 2" - before it's replaced with "This field exceeds the allowed amount of items" again and the additional string is deleted from the UI,

So seems some things aren't working here and/or need aligning between server and client-side.

Happy to approve and merge this PR but first want to check @kjac @nielslyngsoe that you agree there's more to do here.

[kjac]

Uh. We're not seeing the same thing in the UI then 🙈 I will rebuild and test it. Don't merge this just yet.

[kjac]

@AndyButland okay... this is interesting 😆 if the number of items in the editor value exceeds the "max" configuration, the multiple text strings value editor explicitly removes items in IDataValueEditor.FromEditor() to obtain a valid editor value. This of course goes directly against the philosophy of being allowed to save invalid data.

I have removed the offending code now.

The "eager validation" on the client is also not up to par with the current ways of doing things - the validation should not trigger until a save operations takes place. I do think we can live with this for the time being, though.

[Zeegaan]

Looks good, tests good 🚀