Feature/optimizations

[marc2911]

Optimizations: Avoid redundant extra work

1. optimized src gen pipeline to not recompile all files whenever a single one changes

found out via Debug.Log() that we actually regenerate all files whenever only a single one changes

• introduced some container model that can compare the syntax to tell Roselyn whether that file actually changed
• comparing the whole syntax string is potentially also expensive but probably less so compared to the I/O overhead of generating files
• but at least we dont miss any changes that way! future work can make this more fine-grained to check only the declarations we care about.. i couldnt make that reliably work

2. removed redundant enumerations

fix double enumeration issue when calling

enumerable.ToList().ForEach()

to

foreach(var x in enumerable) {}