…370-pairs-query-pagination-sorting-and-filtering

…sorting-and-filtering

- separate filter args for the 2 pairs queries
- handle case when pagination argument is undefined

- create PairMetadataBuilder class to handle filtering
- extract filtering methods in separate service

- renamed 'filterablePairs' query to 'filteredPairs'
- remove unused imports
- made all methods in Pairs filtering service return a promise for unified usage
- moved PageData to common module

- update wording on deprecation reason and pagination exception message