The rolldown plugin hook could return an object map, cast it to string
at node, and decode it has unnecessary json overhead at rust. So here
export an new function to let rolldown could using `JSONSourceMap` to
generate `Sourcemap`.
The sourcemap implement port from
[rust-sourcemap](https://github.com/getsentry/rust-sourcemap), but has
some different with it.
- Encode sourcemap at parallel, including quote `sourceContent` and
encode token to `vlq` mappings.
- Avoid `Sourcemap` some methods overhead, like `SourceMap::tokens()`
caused extra overhead at common cases. Here using `SourceViewToken` to
instead of it.
