Add more descriptive messages to thrown exceptions

[StrongestNumber9]

Description

All of the thrown exception messages should be more descriptive. Below are some examples:

rlo_06/src/main/java/com/teragrep/rlo_06/Fragment.java

Line 79 in b846414

throw new IllegalStateException("fragmentState != FragmentState.EMPTY");

rlo_06/src/main/java/com/teragrep/rlo_06/Fragment.java

Line 97 in b846414

throw new IllegalStateException("fragmentState != FragmentState.WRITTEN");

rlo_06/src/main/java/com/teragrep/rlo_06/Fragment.java

Line 107 in b846414

throw new IllegalStateException("fragmentState != FragmentState.WRITTEN");

rlo_06/src/main/java/com/teragrep/rlo_06/Fragment.java

Line 115 in b846414

throw new IllegalStateException("fragmentState != FragmentState.WRITTEN");

For example toBytes() could be refactored:
fragmentState != FragmentState.WRITTEN
->
Can't convert Fragment to bytes: Unexpected FragmentState, expected to be "{expectedstate}", was "{currentstate}"

Use case or motivation behind the feature request

The messages are currently not very helpful as it is hard to distinguish which operation caused the exception and why, especially without stacktraces.

Related issues

teragrep/pth_06#330

Additional context