Add a 3rd Embed Code type for only Approved Changes in Dynamic Tag Manager

[#1]

I have multiple clients asked for the ability to generate a DTM JS library for only the approved changes.

This would allow them to test the code about to be released to production without any changes currently in development getting in the way. It would also alow for a more stable version of the code to be deployed into staging environments.

Currently there are only 2 code versions:

1. Staging which is actually all changes in development
2. Production, all published changes. 

I would suggest the current "Staging Embed Code" be relabeled to "Development Embed Code" and the new option for approved changes be added with the "Staging Embed Code" label. 

[#2]

This is one of those few places that TMS competitors beats DTM's capabilities. DTM needs more library environments