Bytecodes cleanup: promote TIER_{ONE,TWO}_ONLY to properties

Instead of
```
op(FOO, (left, right -- res)) {
    TIER_TWO_ONLY
    <actual code>
}
```
I'd like to be able to write
```
tier2 op(FOO, (left, right -- res)) {
    <actual code>
}
```


### Linked PRs
* gh-115815