Fix tests, comments, and formatting for e2e/parse

e2e/parse/conversation/message.go

e2e/parse/conversation/message_test.go

e2e/parse/conversation/partner.go

e2e/parse/conversation/partner_test.go

e2e/parse/conversation/ring.go

e2e/parse/conversation/ring_test.go

e2e/parse/conversation/store.go

e2e/parse/conversation/store_test.go

e2e/parse/firstMessagePart.go

e2e/parse/firstMessagePart_test.go

e2e/parse/messagePart.go

e2e/parse/messagePart_test.go

e2e/parse/partition.go

e2e/parse/partition/multiPartMessage.go

e2e/parse/partition/multiPartMessage_test.go

e2e/parse/partition/part.go

e2e/parse/partition/part_test.go

e2e/parse/partition/store.go

e2e/parse/partition/store_test.go

e2e/parse/partition_test.go