fix(ParasService): adjust endpoint to use historicApi, fix endingOffset bug (#735)

* add historicApi to crowdloans-info

* add assertQueryModule check

* add historicApi to crowdloans

* add historicApi to leases-info and leases/current

* add historicApi to auctions-current

* add historicApi to paras

* fix endingOffset bug

* adjust tests to reflect historicApi

* cleanup

* inline docs

* lint

* Update src/services/paras/ParasService.ts

Co-authored-by: Zeke Mostov <[email protected]>

* adjust lease_period_index

* lease period index edgecase

* adjust leasePeriodIndex to be null not BN_ZERO

* update docs

Co-authored-by: Zeke Mostov <[email protected]>