Transaction support for signing and timed service - 2

[netmackan]

Cleanup of the commits from #76

Describe your changes

From @3keyroman:

There are use cases, when siging worker needs to be executed in transaction because it interacts with the database. Typically, when the keys are stored in the database, or some other information needs to be updated during signing execution.

This implementation introduces feature to turn on the transaction handling for other use cases then for key usage counter or archiving. Specifically for signing and timed services.

There is a new interface requiresTransaction implemented, which is false by default.

How has this been tested?

Checklist before requesting a review

• I have performed a self-review of my code
• I have kept the patch limited to only change the parts related to the patch
• This change requires a documentation update

See also Contributing Guidelines.