[core split] Service: rocksdb

[Xuanwo]

This issue tracks splitting the service rocksdb out of core as part of the core-split effort.

Tracking issue: #6829

Please follow the steps in the tracking issue strictly:

• keep public API/behavior unchanged;
• move code into the new crate layout described there;
• add/update feature flags and tests as required;
• open a PR and link it to Tracking issues for RFC-6828: Core #6829.

[KarinaMilet]

Please assign it to me.

[koushiro]

Hi @KarinaMilet, are you still doing this? If not, I'll take over.

[KarinaMilet]

Hi @KarinaMilet, are you still doing this? If not, I'll take over.

I'm almost done.