* Rename waku_api to rest_api and underlying rest to endpoint for clearity
* Rename node/api to node/kernel_api to suggest that it is an internal accessor to node interface + make everything compile after renaming
* make waku api a top level import
* fix use of relative path imports and use default to root rather in case of waku and tools modules
RestApi Lightpush endpoint implemented
* Openapi definition for lightpush rest api
* Update waku/node/rest/lightpush/handlers.nim
* Fix install handler naming, added negative test cases and fixes for restapi lightpush
* Fix error handling in lightpush rest handler
* Fix main success case - relay message that comes with pushRequest
* Fix rest relay serdes test with RelayWakuMessage validation changes
* Checking response message tests
