Fix trailing ampersands when empty array passed as query param

[christianwach]

Overview

Fixes this issue on Lab.

Additionally removes the incorrect parsing of any arrays passed as the $query param to CRM_Utils_System_WordPress::url(). The $query param should never be an array because this is handled by CRM_Utils_System::url() beforehand and CRM_Utils_System_WordPress::url() should never be called directly.

Before

Calling CRM_Utils_System::url() with params such as:

$url = CRM_Utils_System::url(
  'civicrm/some/path',
  array(), // This is the `$query` param
  TRUE,
  NULL,
  FALSE,
  TRUE
);

results in a URL of the form:

https://[domain]/civicrm/?page=CiviCRM&q=civicrm%2Fsome%2Fpath&

After

URLs no longer have the trailing ampersand:

https://[domain]/civicrm/?page=CiviCRM&q=civicrm%2Fsome%2Fpath

[civibot]

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[eileenmcnaughton]

@kcristiano one for you - looks sensible to me

[kcristiano]

@eileenmcnaughton It is sensible.

I've applied and run through some testing based upon the issue and related SE comments. I have not found any issues. I think it's good to merge.