Allow extensions to flag PHPIDS html/json fields

Background
==========

PHPIDS scans all HTTP inputs and applies heuristics to identify malicious
submissions.  It relies on a having configuration about the list of fields
we'll process.

Before
======

The function `createConfigFile()` produces the standard configuration as an
INI file.  The configuration was represented as an unalterable string.

After
=====

 * The configuration is represented as an array.
 * The configuration is generated via `createStandardConfig()`
 * The configuration file is no longer used.

Acceptance Criteria
===================

 * PHPIDS still protects most page-requests.
 * The pre-existing PHPIDS policies still apply.
 * Individual inputs for individual pages – such as the `civicase_reload` involved with CRM-20924  – can be flagged as `html`, `json`, or other `exception`s to the PHPIDS heuristics.