JIT Imporve

[fs7744]

• [x] find way to clean roslyn memory i can't clean memory in .net core . Only way is use JIT to do AOT things to make jit not run with user code. But there is AOT base on source generator.
• [x] project structure
• [x] TypeSymbolInfo cache
• [x] skip generate type which already has generated code
• [x] do some test
• [x] doc