MB-58388: Use custom datetime parsers in date range facet queries

[CascadingRadium]

Jira

MB-58388

Description

Related to Date range facet queries:

• The "start" and "end" fields of the Facet Result struct are now formatted with the layout that successfully parsed them in the Facet Request struct. Earlier we always used RFC3339Nano by default which led to disparity between the corresponding fields in the facet request and result.
  Ex - Facet Request Date Range:

      { 
          start : "2014-09-10"
          end : "2015-08-11"
      }
  

Previously the Facet result had

      { 
          start : "2014-09-10T00:00:00Z"
          end : "2015-08-11T00:00:00Z"
          Count: 100
      }

Now it has

      { 
          start : "2014-09-10"
          end : "2015-08-11"
          Count: 100
      }

• Allow a custom date time parser to be added to the date range struct of a facet request, that will override the default date time parser (dateTimeOptional) while parsing the start and end date strings.
• Add error message when the date time parser fails to parse the date string. Earlier if the date time parser failed to parse the start and end strings of the date range in the facet request, no error was thrown and the facet request would be for start and end being equal to 0 time, so facet result was always nil.
• Fix marshalling error for dateRangeQuery struct. If the query had no end / endString, which is the case when upper bound is unspecified, the marshalled JSON always had the 0 time (time.Time{}) as the value for end, now it is omitted from the marshalled JSON.