Make a "Split into word and instantiate macro" intention

From mps-plaintextgen created by [eugenschindler](https://github.com/eugenschindler): DSLFoundry/mps-plaintextgen#9

Productivity improvement: split into word and directly apply a macro, saves one navigation of going through the intention menu.
Moreover, some intentions could be made for often-used macros (such as property macro or copy_srcl macro).

Start by reading the referenced DSLFoundry/mps-plaintextgen#9 issue and locating the existing split-into-word and macro-intention entry points in MPS-extensions. The payload names no files or tests; done would require a defined intention that splits into a word and directly applies the selected macro, with the commonly used macro cases agreed and covered.

Written by the indexing model from the issue text.