Show inline error for invalid entity list name

[matthew-white]

As of #2165, we now show an inline error if the name of a property is invalid:

• Contains an invalid character
• Is an exact duplicate of an existing property
• Is a case-insensitive duplicate of an existing property

This issue is to do the same for entity lists. Even before sending the request to Backend, validate the name of the entity list: that it doesn't contains an invalid character, isn't a duplicate, etc.