[Microsoft Generator CSharp] Exclude Setter Generation for Collection Properties

[ShivangiReja]

Collection properties are currently generating setters. To address this, please add logic in the ModelTypeProvider.BuildProperties() method to exclude setter generation for collection properties.

[jorgerangel-msft]

Original discussion: https://github.com/jorgerangel-msft/Microsoft.Generator.CSharp/pull/51#discussion_r1575046794