Rslint Custom Rule Support

Custom Rule support is a goal of Rslint and we plan to support users to write custom rslint rule based on *AST* info and *Type* Info, we have some ideas but need to explore which is better
* expose *AST* and *Type* through flatast just like https://github.com/microsoft/typescript-go/pull/711, if it's faster for typescript service api users, it maybe faster enough for typescript lint api users, the problem is how to sync it with tsgo implementation and maintain burdern
* only expose *AST* by flatast and call tsgo language service api by ipc(like https://typescript-eslint.io/developers/custom-rules#typed-rules), which is easy to maintain but maybe not faster enough
* source integration: enterprise users can write custom rule using golang and build their own version of Rslint