refs #7189 fixed case when target MD workspace does not have

any experiment info attached to it. Hopefully fixed, as further tests are needed for that.
refs #7189 Issue clear error message if dimensions units are different
refs #7189 ConvertTo MD is able to add lean events to correspondent ws

Problem with convertToMD system test was that the tests were creating MDLeanEventWorkspace and ConvertToMD was trying to add MDEvents to it.
Code modified to be able to reduce MDEvents to MDLean events if found correspondent target workspace.
refs #7189 "Fixed" Unit test which verifies adding one type of

workspace to another

It is dirty fix, as because we have allowed adding MDEvents to MDLeanEvents, we have to disable check of the strict workspace types.
This solution should be reconsidered after ticket #7473 is completed.
Merge branch 'bugfix/7189_ConvertToMD_V2_inSysTests' into develop