we need tests to have deterministic 'idsubdatatable'

 + tests

Refs #6031, #7213, add segment label to top level CustomVariables.getCustomVariables report for customVariableName.

Allow new CustomVariable segments to provide all custom variable suggested values by allowing the suggestedValuesCallback to accept Live.getLastVisitDetails data.

Allow Segments to define multiple SQL columns if the segment value can be matched in any of those fields, and use to define two new segments: customVariableName & customVariableValue.

Adding System test case that showcases the bug: ecommerce report with segment "Page URL" shows 0 data

Refactor API.getSegmentsMetadata and Plugin\Segment so segments are all defined through Plugin\Segment class in dimensions & make sure AutoSuggestAPITest data providers do not use database.