[Flight] Parse Stack on the Server and Transfer Structured Stack (fac…

…ebook#30410)

Stacked on facebook#30401.

Previously we were transferring the original V8 stack trace string to
the client and then parsing it there. However, really the server is the
one that knows what format it is and it should be able to vary by server
environment.

We also don't use the raw string anymore (at least not in
enableOwnerStacks). We always create the native Error stacks.

The string also made it unclear which environment it is and it was
tempting to just use it as is.

Instead I parse it on the server and make it a structured stack in the
transfer format. It also makes it clear that it needs to be formatted in
the current environment before presented.