Tests metadata

Annotate individual end to end tests with things like:
- Whether it should succeed, end with runtime error or end with a static error.
- extvars and tlas
- error formatting settings (in case error is expected)
- native functions
- import callbacks
- Maximum stack
- Maximum number of printed frames on stack trace
- etc.

This is needed to properly test some features and it would be very helpful in unifying the Go and C++ test suites.