Improve quick fix for introducing a cached property ID

The [`Material.SetFloat`](https://docs.unity3d.com/ScriptReference/Material.SetFloat.html) method can take a string name, that is immediately converted to a property ID via [`Shader.PropertyToID`](https://docs.unity3d.com/ScriptReference/Shader.PropertyToID.html). We already have an inspection and quick fix to recognise this and introduce a field with a converted property ID. We can make some improvements:

* When replacing one instance, check to see if there are any other instances in the same file and prompt to replace all.
* Check to see if a field already exists and change text to say something like "Use existing property field 'Whatever'"
* Provide name suggestions to choose from, based on the initial string literal value, but with additional suffixes, such as `PropId` and `ShaderPropertyId`

Start from the existing inspection and quick fix that recognises Material.SetFloat string arguments and Shader.PropertyToID conversion. Trace how it introduces the cached field, then cover the three requested outcomes: prompting to replace other instances in the same file, reusing existing property fields, and offering suffix-based name suggestions.

Written by the indexing model from the issue text.