Use productName as Solution if available + Merge patch and generate logic for settings.json

[Thaina]

Problem

1 - This package will set dotnet.defaultSolution in The settings.json with sln that generated from folder name
This cause unnecessary git change when we have multiple project folder for each platform or the same project in difference machine

2 - Patching did not patch the file exclusions when there is any update of this repo. We need to remove whole settings.json to see any update which is not ideal

Solution

1 - Use productName instead. This would be value that more consistence in the project and reflect state of current project more than just the folder name

2 - I have merge creation and patching logic and also check for each exclude to specified each exclusion if not exist

Suggestion

I have separate the exclusion setting into it's own array, in the hope that we can have toggle setting to specified what to not exclude in the setting

Also maybe specified search.exclude as false for some ascii file, like .unity and .asset so I could search for usage