ST6RI-619: Start, done, entry, exit actions are not rendered (PlantUML)

[himi]

This PR deals with the issue reported in https://github.com/Systems-Modeling/SysML-v2-Pilot-Implementation/issues/424 It shows start, done actions in actions, and entry and exit actions in states.

[himi]

package TestStartDoneEntryExit {
    part p {
        state s1 {
            entry action initial;
            then state s11;

            transition s11 then d11;

            exit action d11;
        }

        action a1 {
            first start;
            then action a11;
            then done;          
        }
    }
}

is shown by MIXED view as:

[himi]

FYI, I found then exit action d11 was not parsed correctly.