Grouping headers (#2496)

* [C]:hammer: using one header file for the postgres data getters
  * Also simplifying the get_edges_* functions
* [C]:hammer: using the header and adjusting internal code
* [C]:wrench: using the pgdata_getter header
* [types]:hammer: cleaning types for maxCardinalityMatch
* :bug: adding missing line of code
* :bug: removing duplicate include

Author: cvvergara