Implement static bytecode verification about tiro

[mbeckem]

Static verification is implemented and currently runs whenever a module is being loaded:

• Bytecode instructions must be decodable, and the function must end with a halting (or looping) instruction
• Module member ids, function parameter indices and local variable indices are checked
• Jump destinations are checked: they must point to the start of an instruction
• Some instances where specific module member types are required (record templates, closures, etc.) are checked

Some checks have been left out for now, even if static verification would be possible (with major effort):

• Reading from undefined variables
• Only use exception handling instructions when inside a handler
• Balance of values on the stack

All of these instructions would need static control flow analysis and are a consequence of invalid codegen.
They are currently still checked at runtime when an instruction is evaluated (which obviously negatively impacts performance).