**Description:**
This PR is to prepare removal of `string-cache`. Actually, this PR does not remove it. Instead, this PR only removes direct usages of `js_word!`s, especially in patterns.
**Related issue:**
- #4946.
**Description:**
Another update to enable bytecheck rkyv feature flag.
Our dep tree is quite tangled with implicit enable (plugin -> rkyv). PR tries to detach some of it while trying to preserve existing behavior as much as it can.