Improve repr string representation of GqlStatusObject

[robsdedude]

Instead of for example

GqlStatusObject(gql_status='12345', status_description='descr', position=<SummaryInputPosition object at ...>, raw_classification='HINT', classification=<NotificationClassification.HINT: 'HINT'>, raw_severity='WARNING', severity=<NotificationSeverity.WARNING: 'WARNING'>, diagnostic_record={...})

the repr string representation is now

<GqlStatusObject gql_status='12345', status_description='descr', position=<SummaryInputPosition line=1, column=2, offset=3>, raw_classification='HINT', classification=<NotificationClassification.HINT: 'HINT'>, raw_severity='WARNING', severity=<NotificationSeverity.WARNING: 'WARNING'>, diagnostic_record={...}>

or similar.

This is more in line with Python's recommendations since GqlStatusObject has no such public constructor:

If at all possible, this should look like a valid Python expression that could be used to recreate an object with the same value (given an appropriate environment). If this is not possible, a string of the form <...some useful description...> should be returned.

-- https://docs.python.org/3/reference/datamodel.html#object.__repr__

To enable the above change, SummaryInputPosition's repr string representation was also changed to contain more information.