Refactored help string generation

Refactored code to generate configuration help strings into its
own private function. The motivation is to use the same function
to generate help strings for both configuration parameters
(existing functionality) and parameter groups (to be added).

Partial-Bug: #1395819

Change-Id: I2c0fd50d50081c633fb50e89eb8c6a84d948f7cc
Merge "Refactored help string generation"