PrimaryClient: Improve error handling / reporting in sendScriptBlocking

[urfeex]

Feature summary

The new sendScriptBlocking method introduced in #425 currently returns a boolean success value.
Instead, it should inform callers on what went wrong.

In my personal opinion, the right interface for that would be std::expected, but since we don't do c++23 here, yet, throwing exceptions would be the most straightforward way.

Alternatively, a custom return type could be used, e.g.

struct ScriptExecutionResult
{
  bool success;
  // Those booleans could also be encoded into a REASON enum. They aren't necessarily all being checked.
  bool robot_mode_allows_execution;
  bool safety_mode_allows_execution;
  bool start_timeout;
  std::string message;
  std::optional<RuntimeExceptionMessage> runtime_execption;
  std::vector<ErrorCodeMessage> error_codes;
};

[urrsk]

An exception is my favorit as, from a using standpoint, people will always see an exception (unless they catch it).
A return type might be overseen and therefore it is hard to guarantee that people will get the guidning.
Though, we will always report it in the log!