In many cases, there is a need to create somewhat nontrivial bytecode. A
recent example is the verkle statetests, where we want a `CREATE2`- op
to create a contract, which can then be invoked, and when invoked does a
selfdestruct-to-self.
It is overkill to go full solidity, but it is also a bit tricky do
assemble this by concatenating bytes. This PR takes an approach that
has been used in in goevmlab for several years.
Using this utility, the case can be expressed as:
```golang
// Some runtime code
runtime := program.New().Ops(vm.ADDRESS, vm.SELFDESTRUCT).Bytecode()
// A constructor returning the runtime code
initcode := program.New().ReturnData(runtime).Bytecode()
// A factory invoking the constructor
outer := program.New().Create2AndCall(initcode, nil).Bytecode()
```
We have a lot of places in the codebase where we concatenate bytes, cast
from `vm.OpCode` . By taking tihs approach instead, thos places can be made a
bit more maintainable/robust.
Martin HS