[x/programs] pass error messages from host functions

[samliok]

Currently if our host function throws an error we propagate it up the runtime and stop executing the program.

Defining a common hostResponse in the host and guest would provide a more descriptive error handling framework. A potential struct like this would give us more programability and allow us to better handle different responses in the guest.

type  MsgLevel  int
const (
	None MsgLevel  =  iota
	Info
	Error
	Panic
)
type hostResponse struct {
	value int64
	level MsgLevel
	message []byte
}

the host function would convert a hostResponse to a smartPtr and then return as *types.Val in order to match the required function signature. Or it can stop program execution by throwing an error.

For example, the getFn host function returns -1 if it cannot find a key in its db. It also returns a -1 if it cannot grab bytes from memory(a more serious error). These errors are not descriptive. Even with the new refactor of #660, some errors should still be passed to the host while others can stop the runtime.

[richardpringle]

Seems like this is linked with #595?

[richardpringle]

See specific comment from the above PR here
#737 (comment)

[github-actions]

This issue has become stale because it has been open 60 days with no activity. Adding the lifecycle/frozen label will exempt this issue from future lifecycle events.

[richardpringle]

Closing this in favour of #595. Host functions (with the exception of external calls) should not return Result.