### What problem does this feature solve? Since SWC already supports [Isolated Declarations in TS 5.5](https://www.typescriptlang.org/tsconfig/isolatedDeclarations.html), Rslib can provide option to enable it to speed up dts generation. https://github.com/swc-project/swc/pull/9086 ### What does the proposed API look like? - Detect `tsconfig.json#isolatedDeclarations ` and enable it by default. - Provide an option to enable / disable it, like `dts. isolated`