The package creation workflow lacks clearer, more informative field validation messages

Steps to reproduce:

1. Create a new Unity project
2. Open Package Manager window
3. Press “+” at the top left corner
4. Select “Create package”
5. Add a new package name and press “Create”
6. Verify that the "Inspector" window displays the package manifest
7. Click the "Edit" button in it
8. From the "Name" field, delete the entered package title
9. Observe the result

Actual results: User gets an error message "Invalid Package Name ''". The error message is inaccurate and uninformative because the "Name" field is empty.

Expected results: 

• If the field is left empty (e.g., data is deleted completely), an error message should be displayed: "Name field is required. Please enter package name".

• If the user enters prohibited characters, a validation message should appear, indicating the issue and guiding the user on how to correct the input.

Reproducible with versions: 6000.3.0a3

Not reproducible with versions: -

Can’t test with versions: 6000.3.0a2 as "Create package" functionality landed only in 6000.3.0a3

Tested on (OS): M1 Max - Sequoia 15.5