Add API to get or save the binary report inside Kover Offline Runtime

[shanshin]

There is a need to add two methods to the kover-offline-runtime API:

• kotlinx.kover.offline.runtime.api.KoverRuntime#getReport()[B - getting a binary report in ic format as an byte array
• kotlinx.kover.offline.runtime.api.KoverRuntime#saveReport(Ljava.io.File;)V - saving a binary report in ic format to a file at the specified path. If the file does not exist, it will be created. If a file with that name already exists, it will be overwritten.

[shanshin]

Implemented in 0.7.5