Add extent range keeping for single-value insert operation

I've forgot to add tests and functionality for single value INSERT operation in implementing MCOL-2044.

For some reason there are two cases when there should be one (multi-valued INSERT assume single value).

Ideally I should delete out single-value INSERT code because it is redundant and change special case of single value INSERT into calling multiple--values INSERT.. This is solution path one. Solution path two (easier in short term) is to add functionality akin that of multiple-values INSERT into code that processes single value insert